Research Octane Number (RON) of FCC gasoline has been studied using Lanlian FCC gasoline and Lanlian aromatization products as feedstocks and LBO-A as catalyst, and research octane number have been put forward with changing weight hour space velocity (WHSV). The mathematical model forecasts research octane number of modified FCC gasoline with changing weight hour space velocity. The results from experimental data are in accordance with the quantitative analytical conclusions drawn from the calculated data.