The optimization of Automated Storage and Retrieval System (AS/RS) can shorten the productive time and improve circulation efficiency, but the discreteness and complexity of the running system threatens the reliability of the system operation. Therefore, this paper establishes a fault petri net for the situation in which AS/RS operates abnormally. An example is provided to demonstrate a fuzzy petri net model of a primary circuit, using fuzzy type-2 sets and numbers to determine the fault cause. The matrix description method is employed to describe the probability of the failure phenomenon. Finally, by changing input conditions for different degrees of various fault simulations, Visual Object Net++ is used to verify the reliability and accuracy of the proposed diagnostic method, which increases warehouse management efficiency.