Abstract: The influence of phase-change coefficients in a cavitation model was studied using a numerical method. By comparing the numerical results and experimental data, the relationships of evaporation coefficients & cavitation number and condensation coefficients & cavitation number are obtained. The results of a 2D axisymmetric hemispherical cylinder under different cavitation numbers show that: different cavitation numbers are corresponding to different phase-change coefficients, and variations of the coefficients of evaporation and condensation have a great influence respectively on the main cavity, secondary cavity, rear cavity, and other types of cavity in cavity shape, collapse position, collapse strength, and so on.