[1] Sun began his career at Ernst & Young in 1977 after receiving his Master of Accountancy degree from the University of Illinois at Urbana-Champaign in 1977[2] and was[when?]

In 2003, he became the president of the Hong Kong Institute of Certified Public Accountants (HKICPA) and served until 2007.

He was also a member of chairman council[clarification needed] of the City University of Hong Kong from April to July 2012.

[9] Ting was imprisoned for false accounting in 2005,[9] and Ernst &Young paid $200m to settle the negligence case out of court in September 2009.

[11] By this time Sun was co-managing partner for Ernst &Young China; in January 2010 Ernst &Young settled another claim in relation to the bankrupt Moulin Global Eyecare, an audit client between 2002 and 2004[10] whose accounts were described by the liquidator as a "morass of dodginess".