What constitutionalism is can not obtain a satisfied answer no matter whether constitution- alism is democratic politics,no matter whether constitutionalism is a real state of constitution,and no matter whether constitutionalism is the restriction,supervision,control and human right protection of rights.However,traditional three comprehensive answers for what constitutionalism is are restricted to objective answers of constitutionalism.As a result,according to the theories of Marx,Emile Durkheim and Max Weber,under value outlook,this paper analyzes and answers what constitutional- ism is.