In order to improve the trajectory tracking accuracy of the manipulator of a hot-line working robot, an adaptive sliding mode control method based on an improved reaching law is proposed. The dynamic model of 2-Dof manipulator is established, and the observer is used to estimate and compensate the external disturbance, and the adaptive law is designed to estimate and compensate the unobserved disturbance. According to the high frequency buffeting problem of traditional sliding mode, the nonlinear function is introduced to improve the reaching law and reduce the influence of buffeting. The prototype verification results show that the control strategy can effectively improve the working accuracy and response speed of the hot-line working robot, thereby enhancing the stability of hot-line working.