Abstract: Moral hazard in social health insurance is becoming a social problem in the economic society reform.In the information asymmetry market, the social consequence of moral hazard from opportunism trend is not only overspending medical fee, but also destroy on confidence construction and trust system.Moral hazard in social health insurance deteriorated relationship between doctor and client.To control the moral hazard, it's necessary to reconstruct people's trust on system and expert based on promoting mechanism, from the viewpoint of trust mechanism.