Abstract: Due to the problems of high centroid height and low stability coefficient in the application of traditional methods in the obstacle crossing automation control of transmission line inspection robots. Therefore, a research on obstacle crossing automation control of transmission line inspection robot based on PLC is proposed. By combining the road condition information collected by ultrasonic sensors and cameras, obstacles are identified. By establishing a dynamic model for the obstacle crossing of the inspection robot, the robot's motion state is described. Using PLC to control the robot's obstacle crossing posture, PLC based automatic control of the transmission line inspection robot obstacle crossing is achieved. The experimental results show that under the application of the design method, the center of mass height of the robot does not exceed 5mm, and the stability coefficient is above 0.85, which can achieve precise control of the inspection robot crossing obstacles.