Abstract: The extracted oil of intermediate base FCC slurry is split into eight narrow fractions with a boiling point interval of 20 °C by vacuum distillation. The aromatic composition and constitution of these narrow fractions were determined by measuring their density, carbon residue and kinematic viscosity as well as elemental analysis, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy and comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC×GC TOF MS). The results indicate that the density, carbon residue and kinematic viscosity of each narrow fraction increase with the increase of boiling point, in particular with a boiling point higher than 420 °C. The aromatics consist of mainly tricyclic and tetracyclic aryl hydrocarbons in the narrow fractions with a boiling point lower than 440 °C; the content of pentacyclic aromatics increases rapidly with the increace of boling point over 440 °C, though the pentacyclic aromatics are also present in the narrow fractions with a boiling point of 400–420 °C. The aromatics in the FCC slurry are highly-condensed and contain a small amount of short-alkyl groups. The heteratomic compounds in the narrow fractions include mainly sulfur- and oxygen-containing compounds, whereas the content of nitrogen- and halogen-containing compounds is very low.