The invention discloses a highway tunnel designing method based on BIM. The highway tunnel designing method based on the BIM includes the steps that 1, according to mapping and reconnaissance data, aterrain model and a geologic model are built, and tunnel surrounding rock grades are determined; 2, a tunnel texture feature library is defined, and a tunnel cross section model library is establishedthrough calculation; 3, according to a project overall design scheme, a tunnel three-dimensional path and cross aisle and inclined shaft space curve model is built; 4, according to design kilometersof all tunnel cross sections, a tunnel main cave subsection model is built; 5, an inclined shaft model, a cross-aisle model and a tunnel portal structure model are built; 6, other tunnel auxiliary engineering measure components including reinforcing steel bars, steel shotcrete, steel frames and electromechanical parts are built; 7, tunneling work amount accounting is conducted, and a BIM model isapplied. According to the highway tunnel designing method based on the BIM, the terrain model and the geologic model are fused with a tunnel main body, three-dimensional paths can be modified in realtime, related drawings are automatically modified, therefore, the purpose is achieved that engineering design information is completely reflected in the BIM model, and model information transfer and application in the later period are facilitated.