A sequence planning algorithm based on multiple-constraint model was proposed to solve the problems in the bending process of complex workpiece. By employing a heuristic search based A* algorithm, the sequence planning was converted to a generalized shortest path problem, and then a multiple-constraint model which includes the factors of bending feasibility, dimensional accuracy and processing efficiency was introduced to optimize the search process. A bend sequence planning system has been realized based on this algorithm. The testing results of the system indicate that the algorithm is efficient and stability, and the planning time of complex bending workpiece was reduced effectively, especially for the workpieces which don’t have the valid bending process.