The oil-containing wastewater was treated by the immobilized yeast cells(pellets) and the effects of factors on immobilizations were studied . The pellets were prepared with polyvinylalcohol(PVA)-sodium alginate(SA).The experimental results indicate that the optimized concentration of PVA and SAwas 7% (w/v)and 1.3%(w/v), respectively. Furthermore, the process of preparing pellets was also investigated,and the optimized procedurewas that the pellets were initially treated by CaCl2 solution with concentration of 2% for 6h, then immersed by the saturated solution of boric acid for another 18h. According to the above-mentioned  method, pellets have high mechanical strength and mass transfer performance , and the final cell activity is about 80% .