Chang C. K. Cavour worked at Library of Congress, Washington, D.C., was a secretary of Ministry of Foreign Affairs, Peking in 1921. Since 1922 he was appointed deputy judge of Peking District Court, in the period from 1922 to 1926 worked as an assistant councillor of Ministry of Foreign Affairs and professor of political science and economics at China University. At this period Chang C. K. Cavour also was elected a vice-Chairman of Foreign Affairs and professor of political science and economics at China University.
In 1923 Chang C. K. Cavour became a vice-chairman of Constitutional Convention, Fukien. February 1927 he was appointed Secretary in the Ministry of Foreign Affairs of the Nationalist Government, and June 1927 - Commissioner of Foreign Affairs for Fukien and concurrently Superintendent of the Maritime Customs for Amoy.
In February 1928 Mr. Chang became a judge in the Central Court of Criminal Appeals, since December 1928 - councillor of Judicial Yuan of the National Government, and since September 1929 - professor of the History of China's Foreign Relations in Government Central University.