Experiments and computational analysis are done to investigate thermal hydraulic performance of a PCHE (Printed Circuit Heat Exchanger) for IHX (Intermediate Heat Exchanger) of HTGR (High Temperature Gas cooled Reactor). After a PCHE is installed in a test loop, thermal hydraulic performance of a PCHE is conducted experimentally in an air test loop. We use the PCHE with the wavy channels of the cross-section of a semicircle whose length and hydraulic diameter are 765 mm and 0.922 mm, respectively, the mass flow rates of air range 80 - 250 kg/h and the maximum inlet temperatures are 350 ℃ and 200 ℃ at hot and cold sides, respectively. The range of the average Reynolds numbers in the PCHE is about 800 -3500. The friction factors were obtained in the present experiment. The friction factors in the wavy channels are by about 50% larger than that of the straight pipe while they are by more than 100% lower than the results from Hesselgreaves’ correlation. The pressure drop predicted by FLUENT agrees with that of the experimental data within 12.6 %. The data of thermal performance is analyzed to obtain overall heat transfer coefficient. The overall heat transfer coefficient ranges about 106~280 W/㎡K$ in the laminar region. The overall heat transfer coefficient increases linearly as the Reynolds number does. It turns out that the effectiveness of the PCHE is about 95 %.