In this paper, the hydrogen embrittlement behavior of laser-arc hybrid welded joint of bainite high strength steel was studied by four-point bending loading under in-situ electrochemical hydrogen charging combined with microstructure analysis and fracture characteristics analysis. The result show that the high temperature gradient during laser-arc hybrid welding leads to martensite transformation in the heat-affected zone, and high welding residual stress is formed in the fine grain zone. The martensitic phase's susceptibility to hydrogen embrittlement, coupled with the high diffusivity of hydrogen along grain boundaries and the localized residual stress gradients, facilitates the nucleation and growth of hydrogen-induced cracks. This process is predominantly observed along the martensitic laths and grain boundaries, culminating in a brittle fracture mode.