Due to the complicacy of the communication control system (CCS) structure and the variations in operating conditions, the occurrence of a fault inside CCS is uncertain and random. Aiming at limitations of the current fault diagnosis of CCS, the paper presents an approach to fault diagnosis of fuzzy fusion based on fuzzy fault tree. Elaborated method considers the characteristic of diagnostic object to establish fuzzy fault tree, convert the index of fault rate into fuzzy number of fault rate, perform the fuzzy analysis for the fault tree, determine the confidence interval of probability of top event, and achieve fuzzy reasoning diagnosis result. The details of fuzzy number design are described in the paper and an application example of the method is also provided. The results show that the proposed fuzzy fault tree analysis method is effective and available for fault diagnose of CCS.