Abstract: The Active Electronically Scanned Array (AESA) antenna is a critical component of an airborne fire-control radar, with its array face composed of numerous Transmit/Receive (T/R) modules. In current engineering practice, the reliability evaluation of AESA antennas is commonly conducted using a voting model based on the failure rate of individual T/R modules. However, this reliability evaluation method, which relies on a voting model, cannot directly account for the performance uncertainty and degradation processes of the AESA antenna array. To address these issues, this paper employs the principles of reliability science and introduces Belief Reliability theory to perform a reliability analysis of the airborne fire-control radar's AESA antenna. First, key performance parameters of the AESA antenna are identified to establish a performance margin equation. Second, the degradation process of the AESA antenna is analyzed, and simulation methods are used to calculate its performance while quantifying the associated uncertainties. Finally, a Belief Reliability evaluation model is established, and the Monte Carlo method is employed to calculate its reliability. The results illustrate the degradation process and reliability level of the AESA antenna array, thereby demonstrating the effectiveness and practicality of the proposed method.