In recent years, interest in the natural gas industry has been increasing due to the augmentation in the use of natural gas. Supersonic separator is a new technology for dehydration of natural gas by inducing pressure and temperature difference by generating swirling in downstream process of energy industry. In this study, compared the Minimum Length Nozzle and the reference model Laval Nozzle which were newly designed for the swirl efficiency and heat flow characteristics of the supersonic separator using the commercial CFD code ANSYS CFX. For representative case, temperature and Mach number distributions were graphically depicted. The pressure loss coefficient and the swirling intensity were obtained from an optimally designed model.