Abstract: The medium-Mn steel with M3 characteristics (multi-phase, multi-scale, meta-stable) is a promising third-generation automotive steel due to its excellent combination of ultra-high strength and ductility. Hot stamping of the medium-Mn steel is a new process combining the steel stamping and quenching, during which the formability and mechanical properties of the steel are improved simultaneously. However, there is an increasing danger that hydrogen-induced degradation of mechanical properties with increasing steel strength grade for medium-Mn steel. For this purpose, the susceptibility to hydrogen embrittlement(HE) of a hot-stamped medium-Mn steel 0.1C-5Mn for different heating temperature were investigated by using electrochemical hydrogen charging, hydrogen permeation test and slow strain rate test (SSRT). The hot stamped specimens have martensite microstructure. When the heating temperature is 850～1000 ℃, with the increase of heating temperature, the grain size of original austenite increases, while the strength and plasticity of experimental steel decrease gradually. When the heating temperature is 850 ℃, a good combination of strength and plasticity is obtained, and the strength plastic product is 22 GPa?%. With the increase of heating temperature, the content of H decreases, while the sensitivity of HE increases slightly at first and then decreases. The H-charged specimens are fractured by intergranular cracking along the boundaries of prior grains. The difference in the original austenite grains did not influence the HE behavior, despite of the biggest grain size, the 1000 ℃ sample is relative immune to HE, suggesting that the strength and ε-carbides are detrimental to the HE resistance.