In the fluid catalytic cracking (FCC) process, the riser is the most important equipment where the reaction taken place. In the riser operation, the feedstock is fed through injectors and mixed with catalyst and steam. A good design and localization of the injectors to ensure rapid evaporation of the feedstock and a good contact of the droplets with the catalyst is important to improve the process efficiency due to a better reagent distribution which ensures a good feedstock conversion and product yields. Hydrodynamic modelling, heat transfer and cracking reactions were studied in this paper using Computational Fluid Dynamic (CFD) in order to evaluate the effect of nozzles design and configuration on the homogeneity of the gas-solid distribution. A 3D model was solved with the Eulerian – Eulerian approach using ANSYS/CFX version 14.0 as calculation tool. The simulation results showed that the distribution of gas-solid depends significantly on the configuration of the feedstock injectors.