Abstract: To determine the distribution characteristics of Cadmium and Arsenic pollution in farmland soils and the related influencing factors in the farmland soils,the Cadmium and Arsenic contents of 70 topsoil samples,four profiles and 10 rock samples from the farmland soils in a typical Karst region of Yunnan province were analyzed. This study demonstrated that Cd concentration in the soils was in range of 0. 05 ～ 3. 86 mg/g,the As concentration in the soils was in range of 11. 9 ～ 301 mg/g; The content of Cd and As element in the deep soil in the region was higher than the screening value; Cd content in rock of the Karst region was in range of 0. 13 ～ 1. 49 mg/kg,the As content in rock of the Karst region was in range of 1. 4 ～ 319 mg/g. The abnormal Cd and As in the soil in the region is mainly caused by high background geological source or accumulation of soil weathering process.