Abstract: The hot isostatic pressing（HIP） test of hydrogen resistant steel HR-2 components manufactured by laser powder bed fusion（LPBF） was carried out. The effects of HIP on the microstructure and mechanical properties were investigated. The results show that, compared with the original printing state, HIP can effectively eliminate the internal pores of the shape, and weaken the microstructure anisotropy. The internal defects sized 10-30 μm within deposits are undetectable after HIP. Computed tomography（CT） scans were carried out for the post-HIP parts and no defects greater than 30.7 μm are detected. After HIP, the main phase of the hydrogen-resistant steel HR-2 is austenite and a small amount of the martensite has almost disappeared. Also, the melt pool morphology in the original deposit disappears, the grain size becomes coarse, and grain morphologies are equiaxed in the XY plane. The grain morphologies in the XZ plane are columnar and the grains used to be <001>orientation become random again after HIP. The grain size becomes coarse due to the high-temperature and high-pressure treatment, which can lead to the decrease of strength and the increase of plasticity. Compared with those of the original print state, the tensile strength decreases from 950 MPa to 724 MPa, the yield strength decreases from 715 MPa to 473MPa, and the elongation after fracture increases from 30% to 35%, which can meet the strength requirements of the GJB 5724standard for HR-2 forgings. The impact absorbed energy of the specimen after HIP is 67.6 J, which is higher than the required impact resistance of the pressure vessel after heat treatment.