Abstract: Selenium nanoparticles were synthesized using Rhodotorula mucilaginosa PA−1 under anaerobic conditions. Synthesis conditions of selenium nanoparticles were optimized by changing substrate concentration, pH and temperature. Selenium nanoparticles exhibited great adsorption activity using a dye malachite green (MG) as a model pollutant. The results suggested that the adsorption kinetics of Se−NPs for MG fit the pseudo-first-order model and Langmuir model. The adsorption process was physical adsorption of monolayer and the adsorption reaction was exothermic. After 5 adsorption and desorption cycles, the removal rate of selenium nanoparticles to MG was still as high as 82.12%. This study showed the potential of Rhodotorula mucilaginosa PA−1 in the bioremediation of toxic Se (Ⅳ) and adsorption removal of MG by biogenic SeNPs.