In recent years, micro-sized electric unmanned aerial vehicle (UAVs) have gained widespread applications in both defense and civilian sectors owing to their advantages of lightweight construction, portability, and cost-effectiveness. However, a significant drawback is the difficulty in discerning and controlling the flight attitude and trajectory of these UAVs when operating beyond the line of sight. Consequently, they heavily rely on remote control for flight operations, leading to a high degree of operational complexity. Hence, it is challenging to maintain the desired characteristics of micro-sized aerial vehicle systems, such as high sensitivity and stability. In this study, we aimed to enhance the longitudinal flight stability of micro-sized electric UAVs. To achieve this goal, control of a UAV’s elevator was utilized to ensure stability in pitch and roll during flight. We employed the Digital Airborne Tactical Communications System (DATCOM) software developed by the United States Air Force to calculate the fundamental aerodynamic coefficients of the UAV. Subsequently, the longitudinal motion state space equation was employed to derive transfer functions for the pitch angle θ and the horizontal stabilizer deflection δe. Furthermore, we utilized Simulink to compare the effects of two control methods, traditional Proportional-Integral-Derivative (PID) and fuzzy PID, on the longitudinal flight stability of the UAV. We aimed to identify the optimal PID values for the UAV. Finally, we validated through practical flight tests that Fuzzy PID can enhance the longitudinal flight stability of the UAV while also contributing to new technological solutions for stability in micro-sized UAV flight.