The purpose of this study is to investigate a method that can improve the velocity characteristics of hydrogen injectors. Specifically, we aim to analyze the physical changes in velocity characteristics as the plunger center within the injector changes and bypass holes are increased. The method of analysis used in this research involves setting conditions based on a mesh matrix control, such as inlet pressure, outlet pressure, and flow direction, to analyze the plunger within the hydrogen injector. Regarding the analytic model, we set the method of heat transfer, where the temperature inside and outside is set at 30°C, turbulence within the flow layer is k-epsilon, and mass and momentum are in a stable condition of total pressure. As a result, the velocity within the plunger designed with four bypass hole can be increased in pressure uniformity at the plunger center as the stroke increases.