Nowadays, in view of the seriousness of the environment pollution and the urgency of raising energy utilization, there is a need to develop green energy. Due to its high utilization rate, Hydrogen fuel cell system is favored by countries all over the world. What the paper studied is the mechanism model of hydrogen fuel cells as well as the influence of H2, O2 pressure difference and relative humidity on the cell voltage and power density with the current density. It is found that the battery performance can be enhanced by increasing relative humidity from 30% to 50% and the difference between hydrogen and oxygen pressure from 5kpa to25kpa within a certain range. More factors will be included for further research, making the model more reliable to be put into use in the green industry.