Abstract: The steel for hi-pressure gas cylinder manufacture is widely used in such market places as medical sector and aviation industry. For services in crucial environments like arctic areas, marine and other special areas, higher low-temperature impact toughness and repeated-impact strength are required for the said steel. The comprehensive properties of the hi-pressure gas cylinder steel can be considerably improved by proper heat treatment processes. With relevant contrast tests, it is identified that owing to the two heat treatment processes, i.e., quenching at 860℃ plus tempering at 600℃ and quenching at 860℃ plus tempering at 650℃, the yield strength of the steel is much higher than that resulting from the normalization process, while the low-temperature impact toughness is of least doubled.