As the main part of social management system innovation，social risk assessment mechanism plays an important role in improving scientific and democratic level of government decision-making. However，this mechanism still has many blemishes，such as，unclear orientation，the lack of neutrality in evaluation subject，imperfect evaluation content，and the lack of rigidity of the statute law in assessment procedure. Therefore，the paper holds that we should perfect this mechanism as the followings：constructing the mode of government-leading and multi-participation in evaluation subject，strengthening the legal authority and legal faith of people in evaluation content，and introduce the ideals of due process to improve the procedures of risk assessment.