In this paper the problem of designing a second-order sliding mode controller for nonlinear systems with bounded uncertainties is addressed. The adding a power integrator technique is applied to develop a new second-order sliding mode control algorithm. It is shown that under the controller thus designed, the resulting closed-loop system can achieve the finite-time Lyapunov stability, which is superior to the similar results in the literature that can only give the finite-time convergence. The performance of the new second-order sliding mode control algorithm is demonstrated by an illustrative example.