Diffusible hydrogen in the weld caused hydrogen embrittlement, delayed cracks, leading to fracture at low stress. In order to research the diffusion behavior of hydrogen, mercury method and gas chromatography was adopt to measure the diffusible hydrogen amount. And residual hydrogen amount was measured at different temperature by vacuum extraction method. Result shows that diffusible hydrogen amount have no relation to the numbers of weld, and the more weld numbers, the longer escaping time; the more alloy content, the lower escaping velocity. After welding, the slower cooling rate, the more escaping hydrogen amount, so the less diffusible hydrogen amount could be measured. Between 100 and 200℃, the escaping hydrogen amount is stable, but the escaping time declines while temperature is higher. Except diffusible hydrogen amount, residual hydrogen amount is related to oxygen content, microstructure and hardness.