Abstract: Studied here in the paper are two heat treatment processes for the AISI 4147 gas vessel steel pipe，i.e.，quenching with the 15%PAG water-based quenching fluid and oil quenching. The influences by the two heat treatment processes on the microstructure and mechanical properties are comparatively analyzed. Also described is the 2-dimension FEM numerical simulation of the quenching of the gas vessel as made of the said steel pipe. The research result shows that after being separately quenched with the 15%PAG water-based quenching fluid，and with the oil，the Rockwell hardness of the tile-shaped specimen of the pipe as resulting from the water quenching is a little bit higher than that resulting from the oil quenching，while the tensile properties of it as resulting from the two different quenching processes are almost the same，but the impact energy from the water quenching is slightly higher than that from the oil quenching；comparatively the quenching process with the 15%PAG water-based fluid brings about higher martensite content，which is good for improving the low-temperature impact toughness of the gas cylinder as made of the AISI 4147 steel pipe.