Abstract: In order to investigate the fracture reason of a quick-release clamp bolt, means such as fracture observation, X-ray energy spectrum analysis, microstructure and hardness examinations were carried out, and the fracture of failed bolt was contrasted with the impacted fracture and hydrogen-embrittlement induced fatigue fracture. The results show that the bolt was fractured due to stress corrosion, and the crack firstly started from the outer surface of the bolt rod. Rough machining and no protection of the bolt surface contributed to the cracks initiation. The anti-corrosive treatment should be adopted to prevent happening the similar failure again.