On the basis of green supply chain, the combing method of entropy weight method and improved TOPSIS method to choose green supplier is put forward. First builds green supplier evaluation index system, then adopts the entropy weight method to get the weight of each index, finally through an example, uses the traditional TOPSIS method and the improved TOPSIS method to choose the supplier respectively and compares the two methods. Results show that the improved TOPSIS method to choose the supplier is reasonable and feasible, and more scientific.