According to the characteristics of unloading of surrounding rocks in mining,tensile strain was used to describe the excavation damage of rock mass.Furthermore a constitutive model on the coupling of damage and elasto-plasticity was obtained and compiled as a user-defined damage model(UDM) of FLAC.Based on these,a numerical simulation of excavation damage of deep rock mass was carried out,the effect of different supporting patterns were analyzed through the simulation of excavation damage zone of the surrounding rocks in deep mining which could provide references for the rational choose of supporting pattern and its construction design.