Abstract: The thermodynamic response characteristics of the hydrogen charging process of the large-capacity and high-pressure vehiclemounted hydrogen storage cylinder is a key issue that needs to be solved urgently for the safe hydrogen charging of hydrogen fuel cell vehicles. Using the CFD model,the thermodynamic response characteristics of the hydrogen charging process of the 70 MPa Ⅲ vehiclemounted hydrogen storage cylinder under different length to diameter ratio,hydrogen charging rate,initial pressure of the cylinder,and precooling temperature were simulated. The results show that hydrogen cannot be regarded as an ideal gas under high pressure,and the influence of gravity on the hydrogen charging process cannot be ignored. The best length-to-diameter ratio of a 100 L hydrogen storage cylinder is 3.55;the precooling temperature has the most significant influence on the hydrogen charging process,followed by the initial pressure of the cylinder and the hydrogen charging rate,which are similar to the conclusions obtained by thermodynamic analysis.