Abstract: A 35MnBH steel caterpillar track section cracked during the bench test. The causes of caterpillar track section cracking were analyzed by means of macroscopic observation, chemical composition analysis and metallographic examination. The results show that the main cause for the cracking of the caterpillar track section during bench test was that the overburnt phenomenon existed in the forging process, and the mechanical properties were reduced. In the process of bench test, the impact, torsion and other complex stresses on the caterpillar track section led to the formation of crack source at the overburnt structure on the surface of the caterpillar track section. The crack propagated rapidly and finally cracking occurred.