A model for silicon anisotropic etching in alkaline solutions is developed based on the surface atom configurations on different crystal planes. The surface atoms are divided into categories according to the atom configurations, and the microscopic etch rates of surface atoms are related to the macroscopic etch rates of different silicon crystal planes. The microscopic activation energies for some typical surface atoms are further calculated by the microscopic etch rates for surface atoms to simplify the fitting procedures. The model has been extended to a simulation system based on a dynamic cellular automaton method, and a series of simulations has been performed using the simulation system for various etching conditions. The simulation results demonstrate agreement with the experimental results.