This paper is to investigate the relationship between board diversity and audit quality. The research sample is from China listed companies between the year of 2009 and 2011, totaling 2,743 observations. Based on the different types of data, we use multiple regression analysis and logit regression analysis to test our research hypotheses. The variable of board diversity is measured by the demography of board members, i.e., gender, age, tenure and education. Moreover, we use audit opinion, audit fees and discretionary accruals as proxy variables of audit quality. The findings of our study indicate that board diversity has a significantly positive effect on audit quality. If using audit opinion as the proxy, the more diverse the board members, the more increasing probability of non-standard unqualified audit reports issued by the CPA. It can also be found in board gender diversity. If using audit fees as the proxy variables, the more diverse the board members, the less audit fees to be paid. There are similar results by using board age variable and education diversity. In addition, if using discretionary accruals as the proxy, the more age diverse the board members, the less discretionary accruals do companies have. The contributions of this paper are to make a supplementary on the management literature of the board diversity and audit quality, and to serve as suggestions to managers in supporting board diversity because enhancing corporate governance can reduce audit risk, so as to improve audit quality.