The water and sand inrush is very factor to influence the safety production of mining. In order to understand the mechanism of water and sand flow in the fracture, the seepage system was designed and manufactured to test the permeability of water and sand in the fractured rock. According to the seepage test, the magnitude of the effective fluidity was in 10^-8~10^-5mⁿ⁺². S^2-n/kg, while non-Darcy factor β ranged from 10⁵ to 10⁸ m^-1. The relationship of the effective fluidity and non-Darcy factor β- (Joint Roughness Coefficient) JRC was fitted using the exponential function. The equations of effective fluidity and non-Darcy factor were obtained by using the genetic algorithm and the fitting parameters were obtained. The main and secondary factors that affect the permeability include the fracture aperture, roughness, concentration and particle size. Through simulation, it was found that the roughness exhibited no significant effect on the pressure field; however, it did have a significant effect on the velocity field. Velocity of water and sand keeps 1.62 m/s, which increases prominently with the JRC increase. The safety regions are deduced under different coefficient n. The study is important to explore the mechanism of water and sand inrush.