His father was then a junior diplomat with the Chinese Government and was posted overseas when Tchen was two years old.
Tchen followed his father to various postings and never returned to China to live, except for two years (1954–56) in Taiwan, where the Nationalist government under Chiang Kai-shek had fled after losing the mainland in the Chinese Civil War.
His father continued to represent the Republic of China government until 1975 when he retired to live with Tchen in Australia.
In 1958, Tchen gained a student visa to Australia to study—at that time, the only way for Asians to enter Australia due to the White Australia Policy.
Eventually, he obtained a master's degree in town planning at Sydney University.From 1966, Tchen worked as a New South Wales government town planner in Sydney.
Harold Holt succeeded Robert Menzies as Prime Minister in 1965 and effectively ended the White Australia Policy by altering the immigration law to allow Asian migration.
After weighing up his choices, Tchen decided to remain in Australia, and gained citizenship in 1971.Tchen was interested in Australia history and had come to the view that one of the factors that brought about the anti-Chinese attitude in Australia that culminated in the White Australia Policy, was the often self-imposed isolation of the earlier Chinese community.