Abstract: Systematical rock physics experiments were conducted on the sandstone samples of Shawan Formation in Chunguang Oilfield, Chepaizi area, Xinjiang. After determining the composition of different pore types in reservoir sandstone, the non-interaction approximation （NIA） model is used to analyze the effects of porosity and pore shape on the elastic properties of the dry frame of sandstone samples. The seismic rock physics model for the rock samples is established by using the non-interaction approximation, and the model results are in good agreement with the experimental results. Based on the experimental and model results, the squirting-fluid model is used to replace the traditional Gassmann equation for fluid substitution, which can also better explain the experimental results of ultrasonic frequency.