Along with the increasing demand for cloud services, the cloud service market has developed rapidly, but it also produced a trustworthy problem with cloud services. Various cloud service trust evaluation model have been proposed for this problem domestically and internationally. They Use direct trust and indirect trust, user evaluation similarity and preference similarity to participate in the process of cloud service trustworthy assessment. However, the cloud service trustworthy evaluation model in the existing research cannot meet the basic properties such as slow growth and rapid decline in the process of trust evaluation. This paper introduces the way of cloud service trustworthy sliding window to strengthen the process of trustworthy evaluation of the entire cloud service. The problem was solved by using a sliding window to satisfy the slow growth property, and then it was verified by simulation experiments that it can effectively solve the problem.