The optimization study of a convergent-divergent nozzle has been conducted to investigate the behavior of supersonic flow through it at various divergent angles and different throat-to-inlet diameter ratios. The k-ε model was employed for flow analysis, with boundary conditions set based on available experimental data. Mach number exhibits an increasing trend with rising divergent angles, leading to the identification of an optimal divergent angle. Additionally, the throat diameter to inlet diameter ratio was varied to perform further analysis. Geometry optimization was based on Mach number trends, with additional analysis conducted at different altitudes. The modeling and meshing were carried out using ICEM CFD, while CFX was utilized for solving the equations.