Abstract: In order to judge the influence of underground mining on the surface settlements above a phosphate mine，the finite difference numerical simulation method and theoretical calculation are used to quantitatively evaluate the surface deformation caused by underground mining activities. After evaluation， the underground mining activities of the phosphate mine have little impact on the safety of surface settlements，and engineering protection measures can be not taken. The research has certain reference value for the safety impact assessment of similar underground mining projects.

Key words: underground mining, settlement, surface deformation