Cryocoolers are devices that are capable of achieving and maintaining cryogenic temperatures for a number of applications such as high‐energy physics, cooling of superconducting magnets, sensors, high‐vacuum production, cryotronics, cryonics, and so on. All the above applications need coolers with high reliability, efficiency, low maintenance, and low cost. The absence of moving parts at the cryogenic temperatures makes the pulse tube (PT) coolers quite suitable for the above applications. In spite of considerable developments in the area of PT cryocoolers, many of the fundamental processes responsible for the cold production are not fully understood. In this work, we present the results of numerical simulations of two‐stage pulse tube refrigerators (PTR) using adiabatic flow of gas through the pulse tube system. A two‐stage PTR is the improved version of single‐stage system to achieve temperature close to 4 K. Assuming adiabatic gas flow through PTs, the algebraic equations for pressure, mass flow, and volumes at different locations have been derived and solved by a MATLAB based program. Using the above, the performance of PTR has been optimized for different operational parameters. The cooling powers predicted by the model have been compared with the experimental data, and they are in good agreement with each other.