Thermochemical sulfate reduction(TSR) is believed to be the main generation mechanism of high-concentrate hydrogen sulfide in gas reservoirs. During the process of TSR, hydrogen sulfide, carbon dioxide and fresh water are the main kinds of products which might meliorate reservoir property of carbonate rock. Five types pf carbonate rock samples from northeastern Sichuan are chosen to determine the alteration of TSR products to carbonate rock with SYS-1 Dissolution Velocity Measurer of Carbonate Rock. Through a serial of simulation experiments, the alteration capability of the same kind of liquid on different types of carbonate rocks at different temperature and the alteration capability of the three different kinds of liquid on different types of carbonate rocks are compared. The dissolution ratio of H2S can be up to 17.09, to micrite at a temperature of 120℃, which shows that H2S has a higher solubility than CO2 and fresh water has a low one to be ignored. The solubility of acidic H2S and CO2 solution to carbonate rocks shows a high-higher-low trend with increasing from the room temperature to 200℃. The solubility of CO2 is maximum at the temperature range of 60～90℃ and that of H2S at the range of 60～150℃. It is concluded that the TSR-generating acidic gas can play an active role in alteration of reservoir rock but it cannot always meliorate reservoir property. The TSR process that leads to alteration of gypsum into calcite can increase porosity of reservoirs, which means melioration of reservoir property.