Abstract: According to the characteristics of thick oil contaminated wastewater in an asphalt plant in Panjin, four strains of microorganism named TA-11, TA-17, HA-9 and HD-1, which can degrade oil and CODCr of oil contaminated wastewater, were picked out from the oil contaminated soil and activated sludge of Panjin pitch plant wastewater treatment system, and then it was immobilized by chemical embedding technique. Through the conditional tests of immobilizing parameters, an improved co-immobilization technique with PVA and sodium alginate was determined, where the immobilizing gel was made from 10.5% PVA, 0.5% Na · Alg, 3% activated carbon and trace auxin. Experimental results showed that the four strains of microorganism immobilized in such a way are able to remove 62%, 65%, 68.5% and 66.5% of CODCr in oil contaminated wastewater after 64 hours, which was much higher than the removal rate by free bacterium.