The tensile deformation behavior and the axial lattice strain response of 1250 MPa ultra-high strength steels with and without hydrogen charging were comparably investigated using time-of-flight neutron diffraction together with the fracture morphology and microstructure observation. Before tensile loading, the axial (110) lattice plane spacing of hydrogen charged specimen was found larger than that of non-charged specimen while the axial (200) lattice plane spacing of the former was smaller than that of the latter, suggesting that the hydrogen atoms occupied the tetrahedral site promoted the increment of axial (110) lattice plane spacing while the balanced internal stress resulted in the proper decrement of axial (200) lattice plane spacing. The necking and ductile fracture after approaching the 1250 MPa tensile strength occurred in the non-charged specimen, while the brittle fracture occurred in the 8.0×10^-6 hydrogen charged specimen at 500 MPa holding during step-by-step loading. The neutron diffraction analysis showed that in the non-charged specimen, the linear elastic deformation was kept up to 500 MPa loading, the nonlinear elastic deformation was observed preferably on the axial (200) reflection at 700 MPa, and then on the axial (110) reflection at 800 MPa; the axial {200} (i.e. <200>//TD, TD—tensile direction) grain orientation-dependent microyielding was observed preferably at 800 MPa while the (211) reflection was still under linear elastic deformation. Comparably, in the hydrogen charged specimen, the nonlinear elastic deformation was observed preferably on the axial (110) reflection at 300 MPa, and then on the axial (200) reflection at 400 MPa; the axial {110} grain orientation-dependent microyielding was observed preferably at 400 MPa while the axial (211) reflection was still under linear elastic deformation. The longitudinally sectioned microstructure observation under fracture surface confirmed the typical <110>-oriented tensile fiber texture in the non-charged specimen while the intergranular cracks along grain boundaries, quasi-cleavage/cleavage cracks and local crystal rotation in various grains of the hydrogen charged specimen. A concept about crystallographic orientation dependent microyielding was employed here to explain the above results, i.e. the hydrogen charging promoted the axial {110} grain orientation-dependent microyielding rather than axial {200} grain orientation-dependent microyielding, and the diffusible hydrogen embrittled the matrix microstructure, accompanying with local plastic deformation.