The invention discloses a caterpillar type walking mechanism of an upper chord examination vehicle. The caterpillar type walking mechanism comprises two pairs of opposite driving caterpillar wheels and driven caterpillar wheels, the same pair of driving caterpillar wheels and driven caterpillar wheels are connected through first connecting rods, the two ends of each first connecting rod are hingedto the corresponding driving caterpillar wheel and the corresponding driven caterpillar wheel respectively, the two first connecting rods are connected through second connecting rods, the two ends ofeach second connecting rod are hinged to the two first connecting rods respectively, the driving caterpillar wheels comprise supporting frames, and two symmetric tension wheels are rotatably connected to the supporting frames and are sleeved with caterpillars. Through the arrangement of guide wheels and clamping mechanisms, an examination vehicle track or any additional facility does not need tobe additionally added on a bridge, instead, the structure of the bridge itself is completely utilized to achieve walking on the bridge, and a large quantity of resources invested in production, manufacturing and installation of the track or the additional facility are saved.