With the aim of improving engine performance, recent trend of fuel injection nozzle design followed by engineers and researchers is focusing on more efficient fuel break up, atomization, and fuel evaporation. Therefore, it is crucial to characterize the effect of nozzle geometric design and the injection condition on fuel internal flow dynamics and the consequent fuel-air mixture properties. In this study, the internal flow and spray characteristics generated by the practical multi-hole nozzles with different nozzle hole diameter and injection pressure were investigated in conjunction with a series of computational and experimental methods. Specifically, the CFD commercial code was used to predict the internal flow variation under the different nozzle hole diameter and injection pressure，and the high-speed video observation method was applied to visualize the spray evolution processes under the non-evaporating condition. Moreover, the Laser Absorption Scattering method was implemented to explore the spray evaporation characteristics. The different nozzle internal flow properties summarized from the computational results could be used to give a comprehensive explanation for the mechanism behind the spray behaviors observed in the experiments. Furthermore, the nozzle hole diameter effects were correlated with the numerical and experimental results under the evaporating and non-evaporation conditions. It indicated that the nozzle hole diameter and injection pressure can alter the dynamic internal flow, liquid jet break up, spray propagation, and the ambient gas entrainment simultaneously. Two of the most important factors, hole diameter and injection pressure, can exerts different effect on the spray break up and evaporation process. When pursuing the optimum geometrical nozzle design, the effect of nozzle hole diameter should be considered from a comprehensive view.