A novel method was discussed for the preparation of petroleum-based mesophase pitch with a large domain structure and an ordered microcrystal structure. A condensation pitch with a certain amount of anisotropic structures was generated from an aromatic-rich oil from FCC slurry oil by heat treatment. The aromatic-rich oil was used to prepare mesophase pitch by inductive thermal condensation with n-heptane insolubles of the above condensation pitch as seed. Inductive effects of seed on mesophase formation and development were investigated by analyzing the properties of thbe carbonized products. Results showed that mesophase pitch obtained by inductive thermal condensation possessed more anisotropic structures, better optical texture, and microcrystal structure when compared to mesophase pitches produced through direct thermal condensation at low or high reaction temperatures. The introduction of seed was conducive to the improvement of mesophase pitch properties by reducing the reaction activation energy and inducing the formation of anisotropic structures at a low temperature.