Abstract: According to the theory and method of particle flow code in two dimensions (PFC2D), the block caving law of natural caving mining method was investigated. Based on the geologic conditions and the physical and mechanical properties of rock in a nickel-copper mine, the caving law in natural caving mining method was simulated by numerical method. The results show that the mechanical mechanism of natural caving method can be analyzed by PFC2D modeling, and the mining process of natural caving method is simulated effectively. The parameter variation of rockbody during the process of mining can be demonstrated easily. The initial caving radius of undercut in the mine is 10 m, and the continuous caving radius of undercut is 22 m. The numerical modeling is effective to guide the mining process of natural caving mining method in the mine.