The train bottom inspection robot adopts a wheeled motion platform combined with a robotic arm and a vision system, running in the train maintenance trench, replacing manual completion of the inspection tasks of the train bottom and side appearance, solving the problems encountered by traditional manual inspection such as harsh on-site environment, high labor intensity, and subjective factors of personnel, thereby reducing the workload of maintenance personnel, improving maintenance quality, and timely and comprehensively eliminating safety hazards in train operation.