The behavior theory of firm hypothesizes that firms with their performance below their expectations will improve the probability of deviant behavior such as fraud and bribery，but less attention is paid to evading social security contributions. This paper argues that firm swith small performance shortfall prefer to evade social security contributions while firms with big performance shortfall prefer high-risk deviant behavior，and firms with performance surplus pay no attention to the social security contribution. Taking A-share listed companies from 2007 to 2018 as samples，this paper examines the impact of performance shortfall on firms social security contributions. The results show that when performance is lower than expected，performance shortfall is positively correlated with social security contributions, market valuation and industry competition strengthen this relationship；when performance is higher than expected，and performance surplus has nothing to do with social security contributions.