In China's security market, a number of listed companies choose to take up the voluntary audit or review on the interim report. Based on the signal transmission theory required by audit, this paper makes a research on the drivers and consequences of the degree of voluntary assurance of the financial information by selecting the data of Shanghai and Shenzhen A-share listed companies from 2008 to 2015. The results indicate that agency costs, performance of the company may have a significantly negative correlation with the degree of voluntary assurance of financial information, and ownership concentration has a significantly positive correlation with the degree of voluntary assurance. Meanwhile, the market has a positive effect on the degree of voluntary assurance.