This paper deal with optimum shape brick masonry vaults under dynamic loads by cellular automata. In this paper, vaults are modeled. Then they are analyzed and optimized under acceleration–time components of Elcentro earthquake. For vault response optimization, the results were used in cellular automata computational model. Then vaults are analyzed and optimized by modeling rules. The results of error range and time of analysis in automata cellular model and FEM software compared. Finally, comparing the results of CA (Cellular Automata) method and FEM (Finite Element Method) method, shows that although precision is less in CA method, but the time of analysis and optimization is so much smaller in it.