With the continuous development of cloud computing, more and more cloud service providers use cloud platforms to provide services for cloud users. The configuration and implementation of cloud services are not clear to the cloud platform, resulting in a lack of trust. Various methods have been proposed in China and abroad to evaluate the credibility of cloud services in response to this problem. However, the objectivity of evaluation is less considered. This study proposes the environmental indicator, using the sliding window combined with subjective and objective evaluation to conduct credibility evaluation of cloud services. It proves through experiments that this evaluation method improves the accuracy of cloud service credibility evaluation.