The Hierarchy Framework and Discrete Event Simulate Model on Research of Plan of Sorting Orders and Optimizing in Distribution Center in Chinese Small Cities

High-tech food industrial base in Hunan need a new distribution center to improve service level, to cut down cost. They buy some high-speed sorting machines, but they have the problem: the investment is limited, the work force is abundance, and the bosses want the low-speed sorting machine works. What our paper describes is how to setup a sorting system, joining the high-speed machine clusters and low speed ones working together, we should not give up the workforce, and we must satisfy what the bosses´ demands. Our paper introduces a method, it is the hybrid framework with constraint optimize. The framework can build up a workflow model to resolve the problems that how many tasks work with limited resource. Finally, we simulate the model with a famous tool: Petri net tools2 in Mat-lab, finding that the service level, cost and utilization ratio of sorting machines are better than before