Hydrogen entering steel results in hydrogen embrittlement of steel. Hydrogen penetrates the pipeline steel through a series of processes of physical adsorption, dissociation, chemical adsorption and diffusion, of which hydrogen adsorption and diffusion are the key steps. The research methods and results of hydrogen adsorption and diffusion were summarized and the future research direction was prospected. The current main method for studying hydrogen adsorption was first-principle calculation. The effects of steel microstructure, phase, and other macro-scale factors on hydrogen diffusion could be analyzed by experiment. The influence of crystal structure on hydrogen diffusion could be simulated by multi-scale simulation calculations, such as finite element numerical simulation, molecular simulation and first-principles. Hydrogen adsorption and diffusion on surface were mainly responsible for hydrogen embrittlement. However, the adsorption and diffusion of hydrogen atoms on steel surface were mainly concentrated on the defect-free αFe surface. The research on the interaction between hydrogen and defects mainly focuses on the bulk phase. There are few reports about the influence of the change of steel surface state on hydrogen adsorption and diffusion. Hydrogen adsorption on the surface with defects requires further research. The effects of surface stress, dislocations, grain boundaries, phase boundaries, alloying elements, and other factors on hydrogen adsorption and diffusion in surface area are needed to be studied in future.