Abstract: The treatment of oily sludge by pyrolysis has the advantage of efficient recovery of pyrolysis tar, and it is an effective way to dispose oily sludge in a harmless and resourceful way. The high content of iron and calcium inorganic substances in oilfield sludge should not be neglected on the distribution of pyrolysis products and the removal of petroleum hydrocarbons. In this paper, the effects of iron and calcium oxides on the pyrolysis characteristics of oily sludge were investigated by using a fixed bed pyrolysis reactor to achieve the resourceful and harmless disposal of oily sludge, leading to the highest yield of liquid (15.97% and 17.60%) at 500 ℃ and the highest yield of gas (6.21% and 7.41%) at 700 ℃ pyrolysis of oily sludge. The addition of Fe₂O₃ not only increased CO and CO₂ in the pyrolysis gas above 500 ℃, but also increased the content of aromatic hydrocarbons in the pyrolysis tar. The presence of CaO not only promoted the formation of long-chain hydrocarbons in the pyrolysis tar, but also increased the percentage of H₂, CH₄ and C₂H₄ in the pyrolysis gas. By adding of Fe₂O₃ and CaO of 10% respectively at 500 ℃, the content of petroleum hydrocarbons in the pyrolysis residue decreased to 1.87% and 1.94%, respectively.