Abstract: Xinjiang is the country’s largest high-quality commercial cotton production base, and irrigation occupies an extremely important position in cotton production. At present, the Corps often uses traditional frequency conversion speed regulation systems, and most of them use classic PID control or fuzzy control. The adaptability is not strong, the control accuracy is low, and the parameter setting and debugging are troublesome. Aiming at the control problem in this irrigation system, this paper proposes a control method of variable frequency constant pressure speed regulation system based on model reference adaptive theory. In the system design, Lyapunov theory is used to solve the adaptive controller and the corresponding control rate. The structure of the frequency conversion speed regulation system is introduced in this article, including PLC, frequency converter, motor, water pump, folwmeter, etc. The mathematical model of the system is established, and the process of implementing model reference adaptive control using Lyapunov stability theory is discussed in detail. Using MATLAB software to simulate and analyze the system under model reference adaptive control, the results show that the output signal y_p of the control object can well match the reference model signal y_r, and has better response speed, motion accuracy and anti-interference ability.