Born in Surakarta, Central Java, he began his political career after graduating from the Universiteit van Indonesië (now the University of Indonesia) in Batavia, Dutch East Indies (Now Jakarta) in 1948.

[1] He later authored a memoir entitled Memoar Oei Tjoe Tat: Pembantu Presiden Sukarno (Memoirs of Oei Tjoe Tat: Assistant to President Sukarno), co-edited by Pramoedya A. Toer and Stanley A. Prasetyo.

The most critical elements in the book include first-hand testimonies of what happened during the first few months of the 1965 killings in Java, Bali and Sumatra and of Suharto's restless behavior during those volatile months, and also testimonies from other eyewitnesses to the events.

Some of the most sensitive materials in his book were derived from his position as a member of a fact-finding committee established by President Sukarno to examine the details and scope of the mass murders from October to December 1965.

Oei had spent more than a decade in jail, where he further collected a wealth of first-hand testimonies of the contested history from other inmates.