AC is to control and manage the access rights of legitimate users who enter the system on the basis of user identity authentication, so that the user's access rights are limited within the allowable range. It is an important part of information security technology. Implementing AC to users through technical means plays an important role in information security. The main purpose of this paper is to use fuzzy mathematics (FMs) and probability theory (PT) to study the access control (AC) of distributed systems (DS). This paper adds trust elements on the basis of the AC model, sets roles for each trust level, and sets a series of permissions for each role. The user determines the trust level to which he belongs by being judged by other users, and then obtains the corresponding authority through the role corresponding to the trust level. Experiments show that by evaluating the trust degree and the reputation value of user behavior, the ability of user trust degree and service and access behavior is greatly improved. Compared with the existing trust evaluation algorithm, it has a good correlation. At the same time, it satisfies the rule of "slow increase and sudden decrease" of the target change trust degree, which can effectively resist malicious users' phishing attacks, bleaching attacks, collusion attacks and other security attacks, and has higher security.