Medical laser has been applied more and more broadly in bio-tissue cutting, but the efficacy and the side effect have never been standardized at parameters level, depending highly on the experiences of the operator, which causes disadvantage for the spread of this technology; while the choice of the technical parameters of the laser form a crucial factor in the developing of the product. To seek for the optimized parameters, we studied the interaction between the tissue such as the parenchyma of the dog′s kidney and Ho∶YAG laser at different energy densities (50～400 J/cm2), in a circumstance of operation simulated via some extra corporeal animal experiments. We got the statistical results of the interaction, the optical micrograph of the slice and the record of the remained thermal effects. We analyzed the influencing factors of the interaction and the evolution of the remained thermal effects. A peak-value exists at about 290 J/cm2 on the unified curve of the efficacy, which can be used as the recommended value in standardizing. The analysis of the influencing factors and the remained thermal effects brings reference to the improving on the medical laser devices.