Brushless motor driven servo actuator for gas engine and dual fuel engine throttle control. It integrates brushless servo motor, reduction transmission mechanism, position feedback sensor and control drive circuit into one integrated unit. It receives standard industrial control signal, accurately control throttle opening, realize air intake and gas flow precise regulation, with high positioning accuracy, fast response and repeat positioning without error. The whole machine is waterproof, oil-proof and dust-proof, suitable for engine compartment harsh working environment.