It is one of the hot issues to motivate more users to participate in mobile crowd sensing tasks and provide high-quality data. As for that in many online incentive mechanisms, questions for the data quality provided by users and credit marks of the users are not paid enough attention, an online incentive mechanisms for sensory tasks and the evaluation of user credit model are proposed in this paper. Based on the reality and history credit of users, the credit updating algorithm model is established and the multi-stage online incentive mechanism ROM based on credit updating is designed. The simulation results show that the algorithm can help the platform obtain better utility and improve the employment efficiency.