A simplified model for the angle of attack tracking in the pitch channel of unmanned aerial vehicles is proposed. Based on the traditional second-order sliding mode control, the stability problems of the fractional power design of the traditional second-order sliding mode are pointed out, and an improved integral second-order variable structure control method is proposed. At the same time, a softening function design is used to construct the symbol function of the traditional second-order sliding mode. And in the selection of sliding mode surfaces, an integral type sliding mode surface was adopted. Finally, the time-varying Lyapunov function was selected and stability proof was provided under sufficient big gain conditions. After the sliding surface approaches zero, based on the approximate treatment of the simplified model, a proof of Hurwtiz property of the sliding surface is provided, ensuring that the angle of attack tracking error approaches zero and the control of the angle of attack tracking is realized . Finally, the control effect of second-order sliding mode control for unmanned aerial vehicle angle of attack tracking was presented through digital simulation. At the same time, the perturbation problem of control variables in the completely unknown situation of the model was considered, and the control effect was almost unaffected. It can still maintain the stability of the entire system and realize the angle of attack tracking, thus it demonstrates the effectiveness of the design method provided in this paper.