Abstract: There are some problems in research of the constitutive relation of engineering rock masses in the classic theory of mining subsidence. In this paper, constitutive relation of engineering rockmasses are deeply studied by using the theories combination of engineering geology connected with modern mechanics. It is suggested that the constitutive relation and its parameters of the engineering rockmasses can be well determined with the back analysis of total information by black box greylization. Analysis of an engineering case provides a satisfactory result which also can be obtained by analyzing the problem of mining subsidence of complicated structure.