Born in Chengdu, Sichuan, Li was born into a scholarly family of officials. His paternal grandfather ruled the large, five generation - tiered household with an autocratic hand, which young Li found stifling, not unlike that depicted in his famous novel, The Family. As a child Li was taught to read and write first by his mother, and later by privately engaged house tutors. It was not until the death of this grandfather in 1917, causing a power struggle which ended with an elder uncle emerging victorious, that he was released to explore the world. As a youngster Li read widely and was deeply influenced by Piotr Kropotkin's famous pamphlet, An Appeal to the Young, which he read at age fifteen. Hugely impressed by Emma Goldman, whom he later referred to as his "spiritual mother", Li started a lifelong correspondence with her.

In 1920, Li enrolled, with an elder brother, in the Chengdu Foreign Language Specialist School to study English. It was there he first engaged in the organization of literary journal Crescent and wrote a number of vers libre. Joining an anarchist organization, the Equality Society, Li became its most prominent member, actively distributing propaganda leaflets.

Three years later, Li moved to Shanghai and subsequently to Dongnan University, Nanjing on the pretext of study, but mainly, as he put it, to escape the feudalistic (fengjian) influence of his family. There he managed to master Esperanto within one year of diligent study and took part in leftist socialist strikes, while remaining active in the anarchist movement, writing a pamphlet on the Chicago Anarchist Martyrs.

On graduation, he left on-board a liner on February 15, 1927 with a friend for Paris, France, for further studies, where he lodged at the 5th arrondissement (three months at Rue Banville, then Rue Tournefort, No. 2). He described his life there as boring and monotonous, taking daily afternoon walks at the Jardin du Luxembourg and evening French lessons at Alliance Francaise. He recalled especially Rousseau's statue at the Panthéon ("I almost knelt underneath it... he whom Tolstoy described as the conscience of the 18th century"), the River Seine and the tollings of the Notre Dame.

"In spring 1927 I was living atop a five - storied apartment at Paris's Quartier Latin, a small lodging full of gas and onion smell. I was lonely, I felt pain, sunlight hardly shone into my room: I missed my homeland and my family." (一九二七年春天我住在巴黎拉丁区一家小小公寓的五层楼上，一间充满煤气和洋葱味的小屋子里，我寂寞，我痛苦，在阳光难照到的房间里，我想念祖国，想念亲 人。)

It was partly owing to boredom when Li began to write his first novel, Miewang (“Destruction”) on a jotterbook. In France, Li continued his anarchist activism, translated many anarchist works, including Kropotkin's Ethics, into Chinese, which was mailed back to Shanghai anarchist magazines for publication. Alexander Berkman was one of many anarchist leaders he met there.

The trials of Italian immigrants Sacco and Vanzetti filled the fervent writer with anger and Ba Jin worked tirelessly to champion their release. Vanzetti apparently was moved enough to reply to the young man from his American prison, with a package of anarchist texts for his readings. Their short correspondence ceased when Vanzetti was executed, along with Sacco, on August 23, 1927. Li published in late 1932 the short story The Electric Chair (电椅) to protest against their execution.

On his return to Shanghai in 1928, Ba Jin continued writing and working on translations. His first novel, Destruction, was released serially by Fiction Monthly in 1929, a foremost literary magazine and earned him many admirers.

During the next 10 years, Li acted as editor to several important publishing firms and periodicals, as well as composing the works which he is best known for – The Family (1931), The Love Trilogy Fog (1931), Rain (1933) and Lightning (1935), the novellas Autumn in Spring and A Dream of the Sea, the short story collection Mengya (“Germination”) and prose writings in Fuchou ("Vengeance") and Shen, Gui, Ren ("Gods, Ghosts and Men").

During the Second Sino - Japanese War, Ba Jin was actively involved in propaganda work against the Japanese invasion, working on the publication Nahan (“Outcries”, later renamed Fenghuo, “Beacons”) with Mao Dun. In the later stages of the war, Ba Jin completed the famous Torrents Trilogy — of which The Family (1931) was the first written — with Spring (1938) and Autumn (1940). Other works of the post war period, like the short novels A Garden of Repose (1944), Ward No 4 (1946) and Cold Nights (1947), contain some of his strongest writings.

During the Cultural Revolution, Ba Jin was heavily persecuted as a counter - revolutionary. His wife, Xiao Shan, died during the Revolution after being denied medical care, and the manner of her death traumatized Ba Jin for the rest of his life. He was rehabilitated in 1977, after which he was elected to many important national literary posts, including chairman of the Chinese Writers' Association (since 1983). The most significant work of his later years is probably the discursive writings in Suixiang Lu (translated as "Random Thoughts", 5 volumes, composed between 1978 and 1986), in which, among other things, he reflected on the Cultural Revolution in a painfully honest manner and asked specifically for a Cultural Revolution Museum to be set up as a deterrent for future generations.

He spoke and advocated Esperanto and in the 1980s was the vice president of the Chinese Esperanto League.

Ba Jin’s works were heavily influenced by foreign writers, including Emile Zola, Ivan Turgenev, Alexandr Herzen, Anton Chekhov, and Emma Goldman, and a substantial amount of his collected works are devoted to translations. His writing style, characterized by simplicity, avoids difficult, abstruse words, and most of his works would be easily understood by anyone with a high school education, making him one of the easiest modern Chinese writers to read.

Ba Jin suffered from Parkinson's Disease since 1983, an ailment which almost completely debilitated him in his later years. The illness confined him to a hospital unable to speak and walk toward the last few years of his life. Ba Jin died of cancer in Shanghai at the age of 100 (101 by Chinese reckoning). His death marked the end of an era for Chinese literature, especially since he was the last major writer to live through the May Fourth Movement. He received the Fukuoka Asian Culture Prize in 1990.

Asteroid 8315 Bajin is named in his honour.