In this paper, 175 non-financial listed companies on SME board in 2019 are selected as research samples. Through the establishment of multiple linear regression model, empirical analysis is conducted to investigate the influence of various factors on voluntary information disclosure from the perspective of agency theory and signal transmission theory. The results show that the degree of voluntary information disclosure of listed companies is significantly positive correlated with company size, and negatively correlated with financial risk, profitability, the company growth and operating capacity, but audit fees have no significant impact on the degree of voluntary information disclosure.