Exploration geologist and mining engineer Yan Liu Tung and Tai Hang Ling Coal Fields, Kwangsi Province, China, 1942-1946. Chief mining engineer Sam Toi Ling Talc Mine, Luck Chuen District, Kwangsi Province, China, 1947-1950. Processing engineer Yan Hing Non-metallic Industrial Minerals Processing Factory, Yan Hing Mining Limited company, Hong Kong, 1951-1956.
Chief mining engineer and mine manager Needle Hill Wolfram Mine, Yang Hing Mining Limited company, Hong Kong, 1956-1970, managing director, general manager, 1970-1972, chairman and managing director, since 1973. Chairman and managing director Chow Hing Investment Limited company, since 1973. Geological consultant, since 1950.