In 1931, Liu officially joined China's diplomatic corps and on 28 January 1932, he was appointed Secretary of the Ministry of Foreign Affairs of the Nationalist Government.

From Taiwan, he resumed serving as ambassador to Canada until 1962, when he was appointed as the Permanent Representative of the Republic of China at the UN, succeeding Tsiang Tingfu.

[4] Before the vote was tabled, Liu delivered the Republic of China's last statement in the UN:[5] "In view of the frenzied and irrational manners that have been exhibited in this hall, the delegation of the Republic of China has now decided not to take part in any further proceedings of this General Assembly... We shall continue to struggle with like minded Governments for the realisation of the ideals upon which the United Nations was founded and which the General Assembly has now betrayed.

[2] During his tenure, on 6 February 1974, he and the Ambassador of the Republic of Vietnam to the Philippines, Duong Hoang Thanh, were handed a diplomatic note of protest by the Secretary of Foreign Affairs the Philippines, Carlos Romulo, after a military show of force involving both countries occurred at Kalayaan, Palawan.

[4][8] After his retirement from government work, Liu moved to the United States where he settled in San Francisco.