The political connection of the accounting firms that whether have the qualification of securities and futures or have not plays a vital role through the credit mechanism， especially institutional credit and the role is also affected by the institutional environment. The empirical analysis shows that the political connection can have a significant impact on the firms' performance especially the rank of political association belonging to city or county and the firms having no the qualification of securities and futures are more susceptible to the influence of political connection. Moreover, by considering the factors of institutional environment such as market level, administrative intervention level and legal level of system environment, we found that different institutional environment factors' impact on firm performance is not exactly the same and its influence on the role played by political connection in firms' performance is also not consistent.