Abstract: In order to reduce the computation of the CAE analysis on assembly models, a method is proposed to rapidly detect the symmetries of static assembly models by taking full advantage of the assembly relationships. The set of the congruent components is taken as the unit for symmetry detection. First, the mating graph is constructed. By using the assembly relationship, the local coordinates of the components are converted to the global ones. Second, the congruent component sets are partitioned in a top-down style according to assembly, part and geometric levels.And then, the symmetries of the congruent component sets are determined by using the single constraint and multiple constraint rules. Finally, according to the order of the congruent component sets, the global symmetries of the assembly CAD model can be gradually determined by merging and verifying symmetries. Experimental results show that the symmetries of the assemblies can be effectively detected. detected.