This paper presents a novel 3-D topography model for micro-manufacturing process simulations, which uses unit vector of the parametric surface as an important parameter to achieve the surface evolution algorithm. According to various physical models of given fabrications, it can be applied to simulations of isotropic/anisotropic etching, deposition, and other processes with surface evolution direction dependence. The simulation results of this model are 3-D visible of variable perspective. Furthermore, simplification is introduced in some special case to reduce memory requirement and calculation time. Some isotropic etching simulations are performed as examples, and the results indicate the accurate simulated surface.