As the parameter assignment methods for inhomogeneous rock have the characteristic of randomicity

the coefficient of variation of the random parameters is defined as inhomogeneity degree of the rock. The computational formula of inhomogeneity degree for the method of Weibull distribution is discussed; and the comparative analysis with shape parameter is pursued. And the computational formula of inhomogeneity degree for rock mineral cell unit is discussed. In addition the influences of inhomogeneity degree on mechanical property of inhomogeneous rock simulation model which bulit by each of these two methods are researched by numerical experimentations. The study results indicate that the difinition of inhomogeneity degree is logical and it can describe the degree of inhomogeneity of rock models which are bulit by different parameter assignment methods. The mechanical properties of inhomogeneous rock are affected by the mechanical properties of cell unit and the inhomogeneity properties of rock and the ultimate strength of the rock will be weakened because of inhomogeneity. For different inhomogeneity rock models

the influence of the inhomogeneity degree on the ultimate strength of rock can be described by the same function relationship which is linear function.