The invention relates to polypropylene/polylactic acid interwoven composite pelvic floor mesh and a preparation method thereof. The mesh is in a meshwork structure. Preparation of the mesh includes: weaving medical-grade polypropylene monofilaments and medical-grade polylactic acid monofilaments to obtain a mesh in the meshwork structure; flushing the mesh, naturally air-drying at normal temperature, and carrying out thermal setting, cooling, cutting and sterilizing to obtain the mesh. The mesh has the advantages such as low sense of foreign matters, high porosity, structural stability and good biocompatibility.