Abstract: The effect of channel height on the thermal-hydraulic performance of airfoil fin printed circuit heat exchangers(PCHEs) was investigated by numerical method based on the impact of channel geometry. Results show that channel height significantly affects the compactness, resistance, and heat transfer performance of PCHE. Under the same Reynolds number (Re=6 000-14 000), the Fanning friction factor f first decreases and then increasesas with the channel height H decreases (i.e., the ratio of channel height to transverse pitch H/S_T=0.12-0.60), with the lowest f observed at H/S_T=0.24. The Colburn-j factor j shows no significant change for airfoil fin channels with H/S_T=0.24-0.60, while an increase in j is observed at H/S_T=0.12. The ratio j/f is suitable for evaluating the comprehensive performance of airfoil fin channels with different heights. When using j/f as the comprehensive performance evaluation indicator, the airfoil fin channel with H/S_T=0.24 exhibits the best overall performance.