The invention relates to an efficient hydrogen energy vehicle power system with an ambient air purifying function. The efficient hydrogen energy vehicle power system comprises a drive system, a gas turbine, a high pressure hydrogen storage tank, a hydrogen compression unit, a hydrogen gas surge tank, an inverter, an electric-power generator, an expander, a storage battery and an exhaust gas treating and discharging system. The high pressure hydrogen storage tank is connected to an inlet of the expander, one path of an outlet of the expander is connected to a hydrogen inlet through a cold capacity recovery device and the hydrogen gas surge tank, and the other path is connected to the inlet of the expander through a hydrogen compression unit and an intermediate tank. A power combiner is connected with the gas turbine and/or the electric-power generator, according to the technical scheme, the gas turbine is replaced with a hydrogen fuel engine, and the power combiner is connected with the drive system through a drive shaft. According to the efficient hydrogen energy vehicle power system with the ambient air purifying function, the gas turbine is combined with the electric-power generator, so that work efficiency of the hydrogen energy vehicle power system is improved. By recycling of exhaust gas heat, air pollution is reduced, and the natural environment can be protected easily.