ABSTRACT When the vehicle cooling system works in negative gauge pressure environment of plateau, it will face the problem of reduced heat transfer performance, which will lead to an increase in vehicle energy consumption. So, there’s important meaning in studying the thermal-hydraulic performance of heat exchangers and optimizing the design of which for negative gauge pressure environments. In this article, experimental study of wavy fin heat exchanger is carried out in negative gauge pressure environment, and then the numerical simulation model is established. The effects of fin size parameters (fin pitch, fin height and fin amplitude) on the temperature field and flow field distribution of wavy fins are studied. Empirical correlations of Colburn j factor and Friction factor f are obtained according to 336 groups of numerical simulation results. The heat transfer coefficient of air side at −44kPa negative pressure is decreased by 34% on average compared with atmospheric pressure, and the friction factor f is increased by 61.5%. The average deviations of correlations for j and f are 2.3% and 2.7%, respectively. The results could be used in engineering practice of design and optimization of wavy fin heat exchangers for vehicle cooling systems operate in plateau environment.