A double power reaching law-based sliding mode control approach is proposed for the low convergence speed and chattering phenomenon in the scheme with conventional reaching laws. This double power reaching law has the characteristic of global fixed-time convergence, which means the upper bound of convergence time is independent of the initial value of the sliding mode. It is proved that, for a class of uncertain systems, the sliding mode and its derivative can converge to the proposed steady-state error bounds in finite time, respectively. A typical simulation is given to validate the theoretical results presented in the paper.