Entrusted audit of construction project has become the main mode of project audit,which realizes the specialization， socialization and elaboration of the audit.However,it also has serious moral risks.Based on entrusted agency theory,this paper analyzes three characteristics of moral risks:endogencity,traction and selfishness.This paper also analyzes four causes of moral risk of entrusted audit in construction project:information asymmetry,unreasonable charge,poor quality of staff,imperfect internal controlling mechanism and legal system as well as incomplete supervision.Therefore,this paper puts forward several suggestions on how to reduce the moral risk of entrusted audit in construction project,such as adopting payment model with incentive factor; enhancing the requirements of employees to improve the quality of professional staff; perfecting rules and regulations to build legal environment,establishing tertiary supervisory mechanism from government， industry to the agent and clarifying the supervision content and methods.