Abstract: It is important to determine rock mass mechanics parameters in numerical simulation. The basic principles of M.Georgi method and Hoek Brown method of determining the mechanical parameters of rock mass are introduced in detail. Taking research on determining rock mass mechanical parameters in Dongshengmiao Lead-zinc Mine as an example，and based on the physical and mechanical parameters of rocks at indoor laboratory tests，the effect of rock joints and fissures was considered to eventually determine rock mechanics parameters.The recovery model of the ore pillar was built by FLAC3D numerical simulation software，to simulate the surface displacement settlement.Then，the simulation displacement curve of three positions at columns and goaf roofs of No.2 ore body were compared with the measured displacement curve at the same place.The comparison results showed that the rock mechanics parameters determined by Hoek-Brown method were closer to the actual situation，which can be used as the basic data for simulating the recovery of rib pillars.

Key words: Hoek-Brown method, M.Georgi method, Numerical simulation, Mechanical parameters of rock mass