In the traditional trust management model of grid computing,it is difficult for grid service providers（GSP） to effectively evaluate and manage the trust degree of a huge number of grid users,and to resist Whitewash attack and ensure the safety.In order to solve these problems,a cloud model-based subjective trust management model for grid users is proposed.In this model,the trust degree of users in the grid domain is managed by the user trust agent（UTA）,and GSP only needs to evaluate the trust of UTA with the help of cloud model.Experimental results show that the proposed management model,in accordance with grid architecture as well as with the fuzziness and uncertainty of trust,overcomes the disadvantages of the traditional trust recommendation method and makes the evaluation of trust more accurate and reasonable.