The vent or opening is called nozzle. The objectives are to measure the flow rates and pressure distributions within the converging and diverging nozzle under different exit and inlet pressure ratios. Analytic results will be used to contrast the measurements for the pressure and normal shock locations. In this paper computational Fluid Dynamics (CFD) Analysis of various performance parameters like static pressure, the Mach number, intensity of turbulence, the area ratio are studied in detail for a rocket nozzle from Inlet to exit by using Ansys Fluent software. From the public literature survey the geometry co-ordinates are taken. The throat diameter and exit and diameter are same for all nozzles. After the simulation the results revealed that the divergence angle varies the mach number and other performance parameters also varies. For smaller nozzle angle the discharge coefficient increases with increasing pressure ratio until the choked condition is reached for varying the divergence angle.