證券及期貨事務監察委員會
Sun was a member of Securities and Futures Commission between 2001 and 2007. In 2003, he became the president of Hong Kong Institute of Certified Public Accountants until 2007. He was also a member of chairman council of City University of Hong Kong from April to July 2012. Sun was later appointed as Director of Audit of Hong Kong in July 2012.