Abstract: Peat was used as biosubstrate and mixed with aged oily sludge in the ratio of 1∶1, and the field experiment was conducted to study the influence of peat on the bioremediation of aged oily sludge by landfarming. The results showed that after 26 months of field test, the bioremediation efficiency of aged oily sludge was significantly enhanced by adding peat, and the total petroleum hydrocarbons (TPH) of oily sludge was reduced by 38.9%. The physicochemical properties of oily sludge was obviously improved, the salinity and alkaline concentration decreased significantly with the pH being reduced from 8.7 to 6.9 and salinity from 20.3 g/kg to 7.3 g/kg, the content of organic matter increased by 17.3%, and the available nutrient elements of N, P, K increased significantly. Compared with natural attenuation, the enhanced bioremediation of aged oily sludge with peat could increase microbial quantity and biodiversity.