In this paper,we select listed firms in Shenzhen Stock Exchange Marketing during 1991—2002 as samples and study whether listed firms' financing decision depends on timing and the effect of timing is persistent in China.We find as follows:listed firms' financing decisions have timing phenomena;when the external financing decreases,the effect of market timing is persistent;when the external financing increases,there is no persistent effect,and why?It mostly because: listed firms in China have the preference of equity financing,which have the policy' constraints,and the policy is often to be changed.Many firms' performance is bad and they can't reach the standard of equity financing,so they depend on the debt financing.