Oil sludge is generated during oilfield exploration, transportation, and petroleum refineries. Because of the lack of an effective disposal method, oil sludge has caused severe environmental pollution and issues. Pyrolysis is one of the effective and environmentally friendly ways for oil sludge reduction and energy recovery. In the present work, the fast pyrolysis of oil sludge and product distribution were investigated using the PY-GC/MS detection technique. The results indicated that the cracking of oil sludge increased, and heavy hydrocarbon products were increasingly decomposed into light hydrocarbons with increasing temperature. CaO and NiO catalysts effectively promoted the deep transformation of the products. In particular, NiO was able to increase the conversion of aromatic products significantly. This work clearly demonstrated that the catalysts have profound effects on the fast pyrolysis of oil sludge into light hydrocarbons.