As a kind of external supervision mechanism, external audit has the function of corporate governance to help decrease the cost stickiness caused by agency problem. In view of this, based on Chinese A-share listed companies from 2005 to 2011, this paper examines the influence of external audit on cost stickiness. Our research shows that there exists cost stickiness in China’s listed companies. Compared with the cost of sales, the cost of management is stier, which provides additional evidence for the agency of cost stickiness. External audit of high quality can help to alleviate the agency conflict and whereby reduce cost stickiness triggered by management opportunism behavior. At the same time, we find that the level of cost stickiness differs in enterprises with different ownership nature, and the effect of external audit in reducing cost stickiness is also different. Specifically, compared with the non-state-owned enterprises, the cost stickiness of state-owned enterprises is more serious and the effect of external audit is more significant.