Abstract:The balance of assembly line has a great effect on the output of products, and is also a problem to be dealt with at the phases of designing and reconfiguring. Aimed at the current assembly line balancing problem type2(ALBP2), a multiobjective model was proposed, taking task sequence constraints, task zoning constraints and workstation related constraints into account, to minimize cycle time and workloading smoothness index. First, a dynamic step length method was applied, which gradually shrank the searching span of cycle time, to improve the efficiency of computing. Then, an improved PSO algorithm based on a Back Algorithm (BA) was introduced to promote the rationality of tasksallocating. After that task allocation matrix was described to show details of task allocations in stations and clarify the result. Finally, a case was illustrated to prove the effectiveness of the proposed method.