To evaluate the influence of power, irradiation time, energy of per pulse and frequency on ablation effect of pulsed Ho:YAG laser, five canine esophagi were studied. We irradiated the mucosa in different power and different irradiation time. For the same power, the samples were divided into two groups: the high energy per pulse low frequency (H)group and the low energy per pulse high frequency (L)group. The two groups were paired. We compared the effects of ablation effect in different laser settings. The results reveal that the ablation effect is positively correlated to the power and irradiation time. The ablation in H group is more obviouse than that in L group. When Ho:YAG is used in high power, ablation is the main biological effect.