This paper explores the determinants of audit quality from the perspective of audit demand based on the ultimate ownership theory and the principal agent theory. We choose Ashare listed companies data from 2006 to 2010 to discuss the connection between ultimate controllers and the selected audit firms. The evidence indicates that firstly, companies switch ultimate controllers much more frequently than switch their audit firms. Secondly, the change of ultimate controllers character will also cause the accounting firms switch. Thirdly, when the ultimate controllers are changed from nonstate controller to state controller, the audit quality will be reduced. The findings reflect the ultimate ownership is one of the main determinants of the audit quality of listed companies.