A tetrahedral mesh virtual cutting method based on route separation comprises the steps that 1, data of a tetrahedral mesh is read, and a surface triangular patch set of the tetrahedral mesh is obtained; 2, a collision detecting thread is started, and a thread from the surface triangular patch set to a screen is displayed; 3, after collision detection occurs, track discretization of a tool is started, feature point processing is carried out, and meanwhile selection of an optimal route is started; 4, a tetrahedron shared by two first points on the optimal route is separated; 5, the two points in the step 4 are deleted. In the cutting process, each colliding patch is evaluated through an evaluation function, the optimal point is selected to serve as a route of a cutting track, and then tetrahedron separation is carried out; due to the fact that only topological separation exists in the cutting process, and no pathological tetrahedrons are generated, the stability of finite element computing is improved, the number of the tetrahedrons is not increased, and the computing speed is kept.