This paper proposed a variable rate reaching law-based adaptive sliding mode control scheme for electromechanical servo systems with lumped uncertainties including friction torque, load torque and disturbance torque, etc. Firstly, a hyperbolic tangent auxiliary function is presented to construct a novel variable rate reaching law, which can adjust the convergence rate of the sliding mode variable. With the proposed reaching law, a faster convergence rate is achieved before reaching the deceleration point, and the chattering issue can be reduced after the deceleration point. Then, an adaptive sliding mode controller is designed to guarantee that the system position output can track the desired trajectory quickly and stably. Meanwhile, parameter updating laws are developed to estimate the upper bound of the square of the uncertainties, and thus the continuity of the control signal and the reduction of the chattering are both guaranteed. The error convergence performance of the proposed scheme is analyzed through the Lyapunov stability synthesis, and comparative simulation results are given to validate the effectiveness of the proposed scheme.