High fault tolerance, reliability, safety, and dynamic response are critical development goals for the variable pitch control system. The system needs to adjust the pitch angle to achieve maximum propulsion efficiency in various operating conditions. The pitch control system utilizing a dual-redundancy electro-hydrostatic actuator (DREHA) has emerged as the preferred option for future pitch control technology, owing to its exceptional reliability and safety. Therefore, this paper develops a mathematical model of the pitch adjustment system driven by a DREHA is developed in this paper, and simulates and analyzes potential faults. The operating state of the actuator is monitored using an extended Kalman filter algorithm, and an adaptive fault threshold method is employed for diagnosing and switching. The simulation results demonstrate that the fault-adaptive switching strategy developed in this paper exhibits rapid and accurate fault detection and processing capabilities. It can promptly identify faults and seamlessly switch be-tween the active and backup EHAs, effectively reducing the impact of faults on the performance of the entire pitch control system.