Choosing the A-share listed firms in China during 2000 and 2012 as a study sample， the paper studies empirically local government promotion and its influence on firm innovation． Meanwhile， this influence is analyzed in detail from three dimensions of firm characters: property rights， the degree of marketization， and the firms’political connections． It is found that the incentives created by the impending promotion of local politicians will reduce the firms’innovation quantity and quality． The negative effect is stronger if the firm is local state-owned， or if the city’s marketization degree is lower， or if the firm has a political connection． After a further examination， it is found that the firm would establish a political relationship by charitable donations rather than rent-seeking， consequently to further squeeze out innovation． The results not only enrich the research on the impact of impending political promotion， but also offer clear policy implications on deepening the scientific and technological system reforms and accelerating firms’technological innovation.