Abstract: This study focused on the treatment of refined soybean oil wastewater by Trichosporon fermentans. Firstly, the yeast was immobilized with sodium alginate and the prepared magnetic carrier, respectively. Then, the yeast, magnetic carrier, sodium alginate-immobilized yeast, and magnetic carrier-immobilized yeast were used to treat refined soybean oil wastewater, respectively. The comparative analysis of the treatment results showed that the magnetic carrier immobilized yeast treatment of refined soybean oil wastewater at 36 h was the best among the four substances. The pH value of 6.0 was more suitable for the growth of immobilized yeast on magnetic carrier. The OD₆₀₀ value of yeast in wastewater treated after 36 h was 19.78. By studying the treatment of refined soybean oil wastewater by magnetic carrier specified yeast under different pH values and inoculation conditions, the optimal conditions for wastewater treatment were pH value 6.0, inoculation amount 10% and culture time 36 h. Under these conditions, chemical oxygen demand value was 2 430 mg/L.