An efficient cryocooler is one of the essential requirements for cooling of Infrared (IR) sensors to low temperatures in high resolution night vision systems. A regenerator is an imperative component of cryocooler which has a significant effect on cooling performance of a cryocooler. In this research work a Computational Fluid Dynamic (CFD) methodology based on thermal equilibrium modelling approach has been implemented to analyze the thermal performance of a regenerator under different design conditions. The regenerator was modeled as a porous media with time varying boundary conditions in the commercial software package FLUENT by incorporating the effects of temperature dependent physical properties of both, matrix material and working fluid. Simulations were conducted at different cyclic flow velocities and effect of these variations on temperature swing, pressure drop, in-efficiency, capacity ratio and number of heat transfer units of the regenerator have been studied for design of better regenerators. The results show that any increment in the velocity of flow, increase the temperature swing, pressure drop and in-efficiency while decrease the capacity ratio and number of heat transfer units of the regenerator with fixed geometry. In this research work, it is also concluded that the thermal performance of regenerator strongly depend upon the temperature dependent physical properties of both matrix material and working fluid.