The fluid catalytic cracking unit (FCCU) has for many years been described as the most important unit of the petroleum refinery because it can convert Vacuum Gas Oil (VGO) and other heavy refinery bottoms into useful fuels and light olefins. These conversions take place in the riser, which acts as a reactor in the FCC unit. In addition to steam cracking, FCCU is the second chief producer of propylene through direct catalytic cracking of these heavy fractions to produce basic petrochemicals, such as light olefins. In this study, the FCC unit was optimized to yield light olefin gases from direct crude oil (Arab super light oil) cracking. A four-lumped kinetic model was adopted and applied using the dynamic model in gPROMS software 7.0.7 for the modelling and simulation of the FCC unit. In this work, gPROMS modelling of crude oil cracking was validated with experimental data obtained from the literature to validate the simulation results. Simulation data and experimental data are highly correlated with an R2 0.9908 coefficient of determination. Based on the estimated catalyst deactivation function parameter with gPROMS, the proposed four-lump kinetic model simulated light olefin gas yields.