The hidden rules are neither different from such formal rules as laws and regulations, nor different from such informal rules as ethics, morals, customs and habits, and they are such transformative rules from formal rules and informal rules for the sake of maximization of both sides, which are usually negative and hidden. There are such hidden rules in social interaction as follows: the degree of social interaction depends on the degree of relationship and personal connection; making no distinction between public and private interest，makes favor exchange patterns pervade public power field; common sense instead of regulations is highlighted in social interaction. These hidden rules clear up the belief in law and makes corruption breed and spread. On the one hand, clearing up hidden rules depends on perfection and implementation of formal rules; on the other hand, completion of civil culture, clean government culture and culture of rule of law will replace the hidden rule culture, therefore, the influence of the hidden rules in social interaction on corruption will be eliminated by formal institution and culture.