Abstract: This paper chooses the data from Chinese Listed firms of Growth Enterprise Market(GEM) during 2009-2014, which theoretically pinpoints and empirically investigates the impact and mechanism of top management political connection and overconfidence behavior on the cost stickiness. The results show that firms which have political connection benefits would enhance cost stickiness, and the top managers who are overconfidence would increase cost stickiness as well. Further evidence suggests that the joint effects of political connection and management overconfidence would generate a more stronger and positive power on the cost stickiness. The paper preferably combining institutional setting and management background unexplored in the prior literature, brings insight into the impact of management political connection and overconfidence on the GEM firms' cost behavior, which provides suggestive guidance for better understanding the cost management and strategy, and distinguishing the top management emotional traits and their behavioral consequences.