The research is aiming to solve the slope stability problem for the landfill project of Ordos coal deep processing project conducted by Zhong Tian Energy Co., Ltd. It analyzes the stability and reinforcement measures for the slope of landfill via theoretical analysis and numerical simulation. The first step is to obtain the security coefficient by simulating and calculating the typical side slope using FLAC 3D strength reduction method. Then, it understands the failure mechanism of side slope is overall sliding and pull splitting by analyzing the offset, stress and shear strain increment of the side slope model. Therefore, paving geogrid to reinforce the side slope is proposed in the preliminary treatment plan according to actual situation.