Abstract: In this study, indigenous oil-degrading psychrotrophs were isolated from the concentrated sludge tank of tannery, and optimization and combination of these strains were performed by using the partial factor design method. The immobilized inoculants composed of 4 isolated strains was prepared and tested for oil degradability under low temperature on pilot-scale. The results showed that 10 strains of oil-degrading bacteria which can grow at 4℃were screened, and the maximum oil-degrading rate of single strain was up to 75.36%. 16S rDNA sequencing of the isolated strains Y3, Y7, Y9 and Y10 was conducted, and the results suggestedthat they were members of Ochrobactrum sp., Bacillus sp. and Burkholderia sp., respectively. The immobilized bacterial agents were prepared by the mixed bacteria, and the bacteria were added to the airlift bioreactor. Under the conditions of the inoculating amount of 2.5% (volume ratio), at ambient temperature of 13-15 ℃ for 48 h, the oil removal rate of the leather wastewater containing 2.6% (V/V) oil could reach 86.1%.