Based on the optical tracking system, an algorithm of triangular mesh generation in real-time from 3D scattered data is presented. For the non-uniform cloud of points digitized by optical tracking localizer, this paper supplements Hoppe?s algorithm of surface reconstruction and puts forward the sampling density and the neighbor value k firstly. With the Marching Cube visualization technique, the novel mesh approximation method can be applied in the surgical navigation system to help the doctors to judge in clinic. The results of many simulations on cadaver in ACL navigation surgery show that this method can generate the triangular mesh to approximate the bone surface effectively and determine the boundary of surface precisely.