Hydrogen fuel cell vehicles have strategic significance to achieve carbon peak and carbon neutrality in automobile industry and transportation industry. In this paper，the global warming potential of vehicle hydrogen supply link，vehicle cycle and fuel cycle of hydrogen fuel cell commercial vehicle are quantitatively evaluated by life cycle assessment method. The emission factors of hydrogen and carbon were calculated under six hydrogen production modes：coal hydrogen production，renewable energy water electrolysis hydrogen production，steam methane recombination hydrogen production，chlor-alkali industry hydrogen by-product，coke oven gas hydrogen production and biological hydrogen production，and three hydrogen transport modes：gas-hydrogen trailer transport，gas-hydrogen pipeline transport and liquid hydrogen tank transport. The life cycle carbon emissions of hydrogen fuel cell commercial vehicles，diesel commercial vehicles and pure electric commercial vehicles were compared. The results show that compared with pure electric commercial vehicles，hydrogen fuel cell commercial vehicles have emission reduction advantages in vehicle cycle，and as hydrogen production gradually shifts from fossil energy to renewable energy，carbon emission reduction benefits of hydrogen fuel cell commercial vehicles will become more significant.