Abstract: There is fractal property in reservoir rocks,the fractal dimension can describe quantitatively the complexity and the heterogeneity of pore structure.According to the principle of the fractal geometry,the pore structure can be studied,and the fractal stochastic model of pore size distribution and capillary pressure can be set up.The fractal dimension of pore structure and size distribution are studied based on the capillary pressure data.The results show that this method is simple and more exact.