Abstract: This study presents a new systematic approach for automatic assembly sequence plan generation by using an integrated framework of the polychromatic sets and assembly information model. The purpose of this research is to propose a unified and integrated mathematical representation which can be managed automatically by computer and optimal assembly sequences can be generated for various different assembly condition. Firstly, the position, assembly sequences and conjunction relations of the original product are simplified into the so-called polychromatic sets and the part information, associate relation and mating relation are arranged, simplified and systematically represented by polychromatic matrixes and the assembly information model is constructed. By doing so, the assembly relation model can be obtained easily. Thirdly, with the model presented above, localization relation equations, obstacle disassembling relation equations and conjunction relation equations can be obtained. Thirdly, a new sequences extract algorithm called assembly sequence generation algorithm based on polychromatic sets (PSAPS) is presented to obtain the feasible sequences of product. A product assembly example is presented to illustrate the effectiveness of the proposed method.