The robustness of lower limb rehabilitation robots is affected by uncertainty. This paper proposes an adaptive sliding mode control method to maximize control performance under reasonable control input. Firstly, the dynamic model of two degrees of freedom (2DOF) is established via Lagrange dynamics. Then, an adaptive sliding mode control method is proposed. This method consists of a recursive terminal nominal sliding mode control gain and a nonlinear control gain, and has the property of finite time convergence to a bound. The simulation results demonstrate the superiority of the proposed method.