In order to improve the walking stability and obstacle crossing performance of inspection robot,and to solve the safety inspection problem of unstructured and complex unknown environment in coal mine,a design scheme of mobile chassis of floating inspection robot was proposed.The structure design and working principle of the floating mobile chassis of the inspection robot was described,the obstacle crossing process of the inspection robot was analyzed,the centroid position of the inspection robot was deduced,and the relationship between the obstacle surmounting height and the posture of the mobile chassis was obtained.The virtual prototype of inspection robot was established by using ADAMS,the walking and obstacle crossing process of the robot on various complex underground roads were simulated.The results show that by using the designed floating mobile chassis,the walking stability of the inspection robot on the underground complex road can be improved,and the inspection robot have smooth operation and good obstacle surmounting ability,the feasibility of the floating mobile chassis design of the underground inspection robot is verified.