In view of the demand for real-time acquisition of information and the superior performance of the robot in environmental detection，the system composition of the designed hexapod spider crawling robot and the analysis and calculation of the obstacle performance are introduced. The robot is composed of six mechanical legs and robot bodies，based on the Stm32f407 chip as the main controller，and uses the PID algorithm to control the whole robot to keep the balance，and completes the real-time response to the operation instruction through the image acquisition system. Based on the center of gravity transcendence，through theoretical study，centroid analysis and numerical calculation，the ability of the robot obstacle surmounting is analyzed，and the maximum height of the climbing staircase and the maximum width of crossing the transverse groove are obtained. This study provides a further basis for the design of a crawling robot.