The ablation resistance of composite material is usually characterized by ablation heat that laser energy is consumed per unit ablation mass. Whereas the characterization ignores the effects of laser parameters. Taking C/SiC composite material as an example, by using a program for the numerical simulation of laser ablation of composite material, the ablation heat of C/SiC composite material is computed for different laser parameters. Effects of intensity, repetitive frequency and duty radio are analyzed. The result indicates that ablation heat is mainly correlated with intensity and duty cycle of the irradiating laser beams. More intensive laser beam causes more severe ablation. Ablation of unit mass requires more than average incident energy if duty cycle of the laser pulses decreases. In addition, it is realized that the repetitive frequency rate of laser has minor effect on ablation as long as average beam intensity and duty cycle are fixed. For C/SiC material, introducing of some instabilities into laser beams would enhance the ablation process, which leads to low ablation heat.