This paper used the formula of layer system offsetting and stress recurrence in the calculation of solid multilayer elastic media. The formulae for calculating reflection and transmission coefficients of P and S-wave can be deduced. This paper tried to calculate several models for an oil field in Xinjiang and discuss the variation of the reflection coefficient with the incident angle. It is shown that the sand with gas is likely to be detected. Using Zoepptitz's equation and the resolution of reflection coefficients of upright incident angle, the authors tested the single interface and the model in this paper respectively, and the results are coincident with each other.