From 1975 to 1990, Charles served in the UN Economic and Social Council for 15 years, mainly serving as the negotiation secretary or executive secretary of international conferences and negotiations.

From 1991 to 1999, he served as Managing Director of Lazard Asia Investment Bank, a leading investment bank, where he made significant contributions to China's investment attraction in the telecommunications, finance, automotive and infrastructure industries. He has also provided senior consulting services to a number of Fortune 500 companies.

In 2003, he served as Chairman of the Investment Committee of the Board of Directors of Applied Materials, Inc. and became the only Chinese director of a Fortune 300 company at that time.