Abstract: Carbonate rocks are widely distributed in Guizhou Province, where groundwater-driven dissolution often leads to engineering geological problems such as karst leakage, collapse, and foundation stability. To study the dissolution behavior and pore structure characteristics of carbonate rocks under natural hydrodynamic conditions, more than 700 days of field dissolution tests were carried out with limestone and dolomite as study materials. Dissolution amounts and dissolution rates of different time periods were used to characterize the change of dissolution state. Surface dissolution morphologies and internal pore structures were examined using digital image processing and nuclear magnetic resonance techniques. Results show that, after nearly two hydrological years, fluctuations in both dissolution rate and dissolution amount gradually decline. The development of dissolution pores on the surface of carbonate rocks is controlled by mineral composition. With increasing dissolution time, dolomite exhibits pronounced selective dissolution and well-developed pores, whereas limestone primarily develops small cracks and displays uniform dissolution. Changes in pore structure of carbonate rocks is mainly affected by lithology and dissolution time. For limestone, pore changes are mainly concentrated in the range of 0～0.1 um micropores, while dolomite presents significant variations in both ranges of 0～0.1 um and 16～25 um. Carbonate rock dissolution is obviously affected by lithology, time, and hydrodynamic conditions, with clear differences between limestone and dolomite. This study provides new insights into the differential dissolution characteristics of carbonate rocks and the evolutionary mechanisms of karst micro-geomorphology under long-term natural dissolution.