In this experiment，edible cassava was added with different amounts of bio-organic fertilizer under two experimental conditions:no exogenous selenium and exogenous selenium.The soil’s total selenium content，selenium form，soil physical and chemical properties，selenium content and proportion of organic selenium in roots were studied to explored the effects of increased application of bio-organic fertilizer on selenium absorption and utilization of edible cassava.The results showed that:(1)under the two test conditions，water-soluble selenium，exchangeable selenium，effective selenium activation rate，pH，and cation exchange capacity，organic matter，root selenium content，root organic selenium ratio were larger than the control after cassava was added with biological organic fertilizer.Among them，water-soluble selenium，effective selenium activation rate，cation exchange capacity，organic matter，and root selenium content were all significantly or extremely significantly larger than the control group under the two treatments of 600 and 900 kg/hm².(2)under the two test conditions，pH，cation exchange capacity and organic matter were positively correlated with effective selenium activation rate，among them，the positive correlation between the amount of cation exchange，organic matter and the effective selenium activation rate reached significant or extremely significant levels.In summary，adding bio-organic fertilizer to the edible cassava during the planting process can improve the physical and chemical properties of the soil，increase the availability of selenium in the soil，and promote edible cassava’s root absorb and utilize selenium in the soil.