Abstract: Carbonate rock can be easily corroded in natural environment. Water is an important factor that causes carbonate rock erosion. The pure water was used to wash the surface of oolitic limestone specimens in the experimental tank. The mechanism of rain or dynamic water on the dissolution of oolitic limestone was studied. The experiment of simulated rain was carried out for 1200 h. After each 120 h(i.e. a cycle), specimens were dried and the surface mico-topography, weight and ultrasonic wave velocity of specimens were measured, and the dissolution rate was calculated based on the change of the micro-topography. The results show that rain can cause calcite matrix dissolution and oolitic detachment on the surface of specimens. During the first to the fourth rain cycles, the calcite matrix on the surface of specimens slowly dissolved and the dissolution rate was 0~0.05 μm·h^-1. During the fifth rain cycle, oolitic detachment occurred on the surface of specimens and the dissolution rate was 0.08~0.47 μm·h^-1. During the sixth to the tenth rain cycles, the calcite matrix on the surface of specimens slowly dissolved and the dissolution rate was 0~0.06 μm·h^-1. Elastic wave velocity did not change during the whole cycling process, indicating that there is no degradation inside specimens.