A pyrolysis study of oil sludge with and without oil sludge ash and quartz sand as solid heat carriers was conducted using a laboratory-scale reactor and thermogravimetric analyzer. The effects of the pyrolysis temperature and solid heat carrier on the product distribution and oil quality were investigated. The results of the oil sludge ash addition case were compared to those of the quartz sand case to evaluate the possibility of using oil sludge ash as a solid heat carrier in the oil sludge pyrolysis process. The chemical characterization of the oil products was performed by FT-IR (Fourier transform infrared spectroscopy) and NMR analyses. Finally, the possible catalytic effect of oil sludge ash and the sulfur transformation pathway were proposed. The results of the experiment demonstrate that the presence of oil sludge ash can increase the oil yield and reduce the optimal reaction temperature from 500 to 450 degrees C. Oil sludge ash can reduce the coke yield and the carbon residue of the oil product and increase the light oil/heavy oil ratio of the oil product to a greater degree than quartz sand. The presence of pyrrhotite in the oil sludge ash was inferred to be the reason why oil sludge ash is able to reduce the coke yield and carbon residue of the oil product. The results of this study indicate that oil sludge ash is a potential alternative to quartz sand as a solid heat carrier in the pyrolysis process of oil sludge for oil production.