To further investigate and refine the mechanism of pre-strain/pre-stress interaction with hydrogen adsorption on steel (Fe-C alloy) surfaces at the microstructural level, first-principles calculations were employed to study the effects of uniaxial pre-strain on hydrogen adsorption and diffusion at C-doped Fe(110) surfaces. The influence of pre-strain on hydrogen adsorption and permeation was explored through three aspects: atomic spatial configuration, binding energy (E_b), and electronic structure, while diffusion energy barriers for hydrogen permeation were calculated with and without C atom doping. Results demonstrate that doped C atoms induce octahedral lattice distortion in Fe crystals across different directions, creating "distortion" on the Fe(110) surface. Variations in distortion degree (D_Δ) at different sites and their distances from C atom lead to inconsistent trends in adsorption configurations (H adsorption height d and unit surface area S_Δ) and binding energy (E_b) under pre-strain. For adsorption configurations, d is coupled by ε and C atom effects: at the TF_pure site (non-C-doped site ), d decreases as S_Δ increases; under compression(ε decreases from 0% to -5%) at TF (C-doped site with C atom directly beneath the site), TFs (C-doped site located closer to the maximally distorted atom Fe₁₃₅) and TF_L sites (C-doped site located farther from the maximally distorted atom Fe₁₃₅), d positively correlates with D_Δ, while under tension (ε increases from 0% to 5%), d negatively correlates with S_Δ. For E_b, as ε increases from -5% to 5%, E_b at TF_pure peaks then declines, whereas E_b at TF decreases initially before rising, and E_b at TF_S/TF_L monotonically increases. Analysis reveals that E_b at TF_S/TF_L positively correlates with the standard deviation (S_α) of the three internal angles in the triangular unit. The diffusion energy barrier (E_∆) trends inversely with E_b. When H adsorbs at C-doped sites, adsorption configuration and binding energy calculations suggest H tends to diffuse inward more readily. However, electronic structure analysis reveals repulsion between C and H atoms, accompanied by increased diffusion barriers compared to undoped cases, causing H atoms to accumulate around C atoms rather than penetrating the bulk phase, thereby inducing hydrogen embrittlement. Adsorption configuration, binding energy, and diffusion barrier calculations indicate that at doped sites (TF_S site), increasing tensile strain facilitates H diffusion into the steel microstructure, whereas compressive strain hinders it. This explains the engineering phenomenon where "higher carbon content exacerbates hydrogen embrittlement tendency under equivalent stress" at the atomic scale. The study elucidates the mechanism of H adsorption on pre-strained Fe-C alloy surfaces from an electronic structure perspective, providing theoretical insights for hydrogen embrittlement research.