Influence of lithology on dissolution rate is helpful to estimate karst carbon sink intensity, which is of great significance to the research on global climate change. Comparative dissolution experiment with standard tablets and local tablets was carried out in a typical small watershed in semi-arid area, southwest of the Jinzhong Basin, Shangxi Province, China. Results show that the dissolution rate (0.122 3-0.532 8 mg/(cm~2·a)) and karst carbon sink intensity (1.713 tCO_2 / (km~2·a) of local rock tablets are significantly lower than those of standard rock tablets (0.254 7-0.551 1 mg/(cm~2·a) and 1.815 tCO_2/(km~2·a)), respectively. This means that the karst carbon sink intensity is overrated by standard rock tablets method. The negative correlation between tablets dissolution rate and contents of acid insoluble further indicates that higher levels of acid insoluble content of local tablets (2.58%-10.86%)than those of the standard tablets (3%) are the major cause for the lower dissolution rate and karst carbon sink intensity. In other words, since there are differences characteristics of formation lithology between local tablets and standard tablets, great error will be produced by using standard tablets to study karst carbon sink effect of different regions. Therefore, in order to accurately calculate the amount of karst carbon sink, it is necessary to use local rock tablets instead of the standard tablets.