In the traditional robust control method, the uncertain boundary is needed in the design of the control law, however, the boundary usually increases the amplitude of the control signal and causes damage to the system. Therefore, this paper porposes a kind of LPs (Legendre polynomials) control law. The total uncertainty of each joint of SCAR Robots is estimated, accordingly, the uncertain boundary is calculated by LPs. Compared with the traditional robust controller, the proposed controller is simpler, requires less computation and less feedback, and eliminates the condition that the upper limit of external interference and parameter uncertainty must be known in advance. The control law proposed is simulated by a SCARA robot manipulator, and the simulation results verify the effectiveness of the proposed control method.