Objective To investigate the reaction kinetics between the stone-dissolving solution and the urinary stone in a model simulating the condition of a kidney for further clinical administration. Methods An artificial upper urinary tract was made by silica gel. Lactic acid prepared in the preliminary study was used to react with artificial stone in the model. The concentration of reaction product in the effluent was measured to identify the reaction velocity. Relationships between the efficiency and dissolution rate or stone surface was investigated. Results The highest utilization rate of dissolution was 100 ~ 150 mL/h. Dissolution efficiency is in positive rela-tion with stone surface. The efficiency correlates with the stone surface and infusion speed in the range of 50~400 mL/h. Conclusions Before dissolution treatment ,the stone should be shattered as deeply as possible to in-crease the surface of reaction. If possible ,the irrigating speed should be as high as possible to eliminate the stone sooner.