A typical Se-enriched tea plantation soil and a non-Se-enriched soil in Guizhou were used as the research objects to investigate the adsorption characteristics of Se(Ⅳ) and its influencing factors of oxoanion. The results showed that Se-enriched tea plantation soil had high organic matter, total Se, and iron and aluminum oxides contents, and exhibited strong Se(Ⅳ) fixation capacity. The results of kinetic model fitting showed that both pseudo-second-order kinetic model (R² > 0.85) and Elovich model (R² > 0.97) were effective in describing the adsorption process of Se(Ⅳ), and initial adsorption rate of Se-enriched soil (α = 25.4) was significantly higher than that of non-Se-enriched soil. Langmuir model was more suitable for describing the isothermal adsorption of Se(Ⅳ) (R² > 0.99), and theoretical maximum adsorption capacity (Q_m) of Se-enriched soil (1.53 mg/g) was higher than that of non-Se-enriched soil (1.18 mg/g). The correlation analysis showed that soil pH, organic matter, and Fe-Al oxides were the most important factors influencing the adsorption of Se(Ⅳ) on the soil. Among the common oxoanions, phosphate had the most significant inhibitory effect on the adsorption of Se(Ⅳ) on soil, and 1 mmol/L PO₄^3- solution could reduce the removal of Se(Ⅳ) by 80%. Fourier infrared (FTIR) spectroscopy results showed that phosphate led to the dissociation of soil Se, whereas both nitrate and sulfate did not affect the adsorption of Se(Ⅳ) on either soil.