Abstract: During the service of oil and gas pipelines, the wall thickness of the pipeline is locally thinned due to the corrosion and erosion of oil and gas, or the pipeline is damaged due to mechanical damage. It is necessary to repair the thinned and damaged parts of the pipeline by in-service welding. However, during in-service welding, the cooling rate is accelerated due to the pressure and flow rate of the medium in the pipe, and hydrogen-induced cracks are prone to occur. The research status and progress of hydrogen-induced cracking in pipeline in-service welding were described in terms of the mechanism,influencing factors, evaluation indicators and prevention methods of hydrogen-induced cracking, which can provide reference for relevant personnel.