Some problems that conceptions of two types of parameters including modulus in tension and compression with corresponding viscosity coefficient and shear modulus with corresponding viscosity coefficient are unclear or these two types of parameters are translated irrationally，are occured in the application of back and positive analysis for viscoelastic model. Due to solve these problems，the conceptual difference of these two types of parameters is analysed firstly. Then，translated relations between these two types of parameters (generalized Kelvin model for hypothesis of constant volume modulus) are established theoretically. Using these translated relations in viscoelastic model for rock and soil，the numerical experiment，discussing these problems mentioned above for back and positive analysis，indicates the internal reason occurring these problems mentioned above and presents the feasibility method solving these problems. At the same time

the thinking solving these problems mentioned above is adopted to the condition of other hypothesis for viscoelastic model.