Abstract: Due to the high work in process (WIP) level for production processes of plastic products,lot sizing problem is discussed in this paper.By analyzing the production processes,a simulation model is built based on the eMPlant platform.By simulation with this model,it shows that the WIP can be significantly reduced and meanwhile productivity can be increased if an appropriate lot size at different stage of the production process is chosen.Moreover,guideline is presented for how lot size can be determined.

Key words: lot sizing, work-In-process, simulation