Abstract: In order to design a lightweight and high efficiency condenser for a miniature refrigeration system with 300 W cooling capacity,a mathematical model is proposed to describe the heat transfer and flow in a parallel flow condenser.A program was developed by using Matlab software to simulate the performance of the condenser which satisfies 450W heating load under certain conditions.The weight and pressure drop curves against the refrigerant flow arrangements and air velocity have been obtained.The influences of different flow arrangements and air velocity on the performance of miniature condenser were analyzed and the optimum flow arrangements and air velocity were obtained.