In order to explore the effects of selenium characteristics and physicochemical properties of different parent soils on selenium availability in red soil regions of southern China. Taking the typical red soil area of Guangxi as the main sampling area, the effects of different factors on the available selenium in soils with different parent materials were determined through the determination of the selenium morphological characteristics and physicochemical properties, and the AMOS path analysis model and soil culture experiment. The results showed that the total selenium content of different parent soils was higher than 0.4 mg?kg-1 in southern red soil region, and the selenium content of granite parent soils was the highest.The parent material content of sand shale is the highest and has the largest range of available selenium content.The overall available selenium content were low.The selenium forms are mainly OM-Se and RES-Se, and the contents of different forms from high to low are as follows:RES-Se > OM-Se> FMO-Se >EX-Se >SOL-Se.The results of AMOS path analysis showed that total phosphorus, organic matter and pH contributed to the distribution of selenium morphology in different parent soils.The influence of total nitrogen in the parent material of quaternary laterite and available nitrogen in sand shale is also noteworthy.The soil culture experiment was carried out using the physicochemical factors with greater contribution.After the addition of exogenous physicochemical factors, the maximum available selenium content appeared in the soil at a certain time and concentration conditions, and the optimal factors obtained in different parent soils were different. Because of the difference of soil physical and chemical properties, the selenium morphological characteristics of different soil parent materials are greatly different. After different physical and chemical factors are added to the soil, the soil selenium will be redistributed due to the change of soil environment.