Abstract: The distribution of diffusion hydrogen in welding zone of HQ130 high strength steel is calculated by using finite element method (FEM).And their effects on weld crack are analyzed.The finite element program of hydrogen diffusion in welding zone is worked out.In the program,the effects of weld heat input (E),temperature,plasticity distortion,surface escaping coefficient of hydrogen etc,on hydrogen diffusion are taken into account.The numerical analysis indicated that hydrogen accumulates seriously near the fusion zone,especially in weld root.This is an important factor to cause crack in this zone.Increasing weld heat input and surface escaping coefficient of hydrogen can decrease hydrogen accumulation in the fusion zone of weld surface,but it is not obviously sin weld root.Increasing dislocation makes hydrogen accumulate seriously in fusion zone.The results of test and analysis indicate that the heat input in the middle weld should be controlled to about 16 kJ/cm to prevent crack generating and propagating for HQ130 steel.