A novel sliding control approach based on double power combination function reaching law was proposed. The proposed reaching law has faster convergence speed in comparison with fast power/double power reaching law, and it also has the characteristic of global fixedtime convergence, which means the upper bound of convergence time is independent of the initial value of sliding mode variables. It was proved that for a class of bounded external disturbance, the sliding mode variable can converge to a proposed steady-state error bounds in finite time, and the value of the steadystate error is less than the previous reaching law. Simulation results show that the validity of conclusion is confirmed.