In order to solve the problem of real-time monitoring the coupling efficiency of 10kW-level optic switch, a safety control method was adopted to monitor the coupling efficiency by detecting the backscattered light inside the working fiber at the output end of the optic switch in real time, and then its coupling failure was prevented. The mapping law and model between coupling errors and signal of backscattered light intensity were simulated and established. Furthermore, the safety control system of the optic switch was designed. And the effectiveness of the method was proved through the simulations and experiments. The results show that the high-power optic switch can carry more than 10kW power for a long time under the guarantee of the safety control system, and the coupling efficiency is stable above 98%. This research can ensure the long-term efficiency, stability and safety of 10kW-level optic switch. It can promote the autonomy of key components in the field of laser manufacturing in China.