In the ERP project implementation, it is an important mean to control the implementing risk effectively that distinguishing and fulfilling ERP project risk sharing responsibilities between the enterprise and the partners. Starting from the three-stage of decision and three-layer structure of main participants, this paper constructs risk sharing index system and constructs model to obtain risk sharing initial proportion for ERP project using AHP, then using the balance of responsibility, right and benefit to convert risk allocation to profits allocation problem. Starting from the goal of maximizing the overall satisfaction of all partners, the paper constructs the second stage model based on Nash negotiation.