The cobalt contents and its affecting factors in soils of Yuncheng district in Shanxi province were studied.The results were summarized as follows:(1)The contents of total cobalt ranged from 1.65 mg/kg to 17.85 mg/kg,with an average of 6.00 mg/kg,which was little higher than the critical level 5 mg/kg,but lower than the average level of China 11.2 mg/kg.The contents of available cobalt ranged from 0.060 mg/kg to 2.235 mg/kg,with an average of 0.694 mg/kg.The total cobalt contents in the main soil types cinnamon soils and fluvo-aquic soils respectively were 6.17 mg/kg and 4.73 mg/kg,and the available cobalt contents respectively were 0.708 mg/kg and 0.589 mg/kg.(2)The main influence factors to the total cobalt contents in soils were parent material,soil forming process,the contents of iron and manganese.Available cobalt contents were mainly affected by parent material,soil forming process and organic matter contents.