The Micro-Electromechanical System (MEMS) optical switches in power systems may be affected by optical control signals during fiber switching, which may cause damage to Optical Time-Domain Reflectometer （OTDR）. In order to solve this problem, this paper proposes a method to optimize the switching path of MEMS optical switches in power systems. After the optical switch performing a complete scan, the accurate optical signal channel power contour map is obtained, and then the switching path is optimized and controlled. Therefore, the MEMS optical switch can achieve the highest relative channel isolation of incident light along the premise of balancing the control channel switching time. The best path for switching control can also be used to minimize the impact of the MEMS optical switch on other channels when switching under the premise of ensuring the switching time, and it will not be affected even in a very complicated channel environment.