Abstract: This paper selects A-share listed companies from 2011 to 2015 as samples to test mediating effect of investors heterogeneous belief on the relationship between accounting conservatism and stock idiosyncratic risk. After the study, it finds that: the accounting conservatism can inhibit investors heterogeneous belief and stock idiosyncratic risk; investors heterogeneous belief can significantly raise stock idiosyncratic risk, that is, they are significantly positively correlated; investors heterogeneous belief plays a partial intermediary factor in the process of accounting conservatism inhibiting the stock idiosyncratic risk, and accounting conservatism affects the stock idiosyncratic risk through the dual path of direct and indirect integration. Therefore, relevant government departments should improve the accounting conservatism, strengthen the construction of information disclosure system, and increase punishment for illegal information disclosure. Listed companies should implement the information robustness requirements, improve management incentive and supervision system, and enhance the overall quality of financial personnel. External investors should combine active learning and training of supervision departments to enhance their risk identification and prevention capabilities..

Key words: accounting conservatism, investors heterogeneous belief, stock idiosyncratic risk