Abstract: In view of the abnormal phenomena such as low plasticity and silvery white spots on the fracture of heavy type H-beam in longitudinal and Z-direction tensile tests. The causes of the above anomalies were analyzed by means of macroscopic observation, chemical composition analysis, metallographic testing, fracture analysis and dehydrogenation annealing test. The results show that the silvery white spots on the fracture surface of the sample were white spots formed by the continuous accumulation of hydrogen to the defects (hydrogen traps). Dehydrogenation annealing could effectively restore the plasticity of the material.