Based on the balanced panel data of Chinese listed firms from 1999 to 2004, this paper studies the relationship between product market competition and dynamic adjustment in capital structure. Results show that, from both static and dynamic perspectives, product market competition and its changes have significant influence on the degree of deviation of a firm' s present capital structure from its targeted one. Specifically, the more intensive the product market competition, the smaller the capital structure deviation. Meanwhile, capital structure deviation tends to decrease in a market characterized by increasingly fierce competition. However, evidence also reveals that product market competition and the speed of the capital structure adjustment are independent from one another.