In order to solve the problems of parameter uncertainty and high nonlinearity of hydraulic servo system,a variable domain adaptive fuzzy control method was proposed.An adaptive law was designed to adjust the parameters of the control system online by using the error information fed back at different times to realize real-time adaptive adjustment,thus the problem of traditional fuzzy control relying too much on fuzzy control rules was avoided.Based on the adaptive fuzzy control system,taking the system error and error change rate as the input and the expansion factor parameters as the output,the self-adjusting function of the expansion factor was proposed to achieve the control of high precision and high response of the hydraulic servo system.The MATLAB/Simulink simulation results show that the variable domain adaptive fuzzy control method effectively improves the tracking speed and accuracy.