This study examines the performance of printed circuit heat exchangers (PCHE) operated at high temperature subject to the influence of inlet conditions. Simulations are made with three cold plates and three hot plates with mass flow ranging from 0.469kg/h to 4.697kg/h. The inlet temperatures of the cold side and hot side are 200°C and 700°C, respectively. The size of the plate is 272×55×1.65mm with straight channel in the cold side and Z-Shape channel in the hot plate. The simulation is carried out for three cases (Case1: Vc = 5 m/s, Tc = 200 °C, Vh = 5 m/s, Th = 700 °C; Case2: Vc = 5 m/s, Tc = 200 °C, Vh = 10 m/s, Th = 700 °C; Case3: V c = 1 m/s, Tc = 200 °C, Vh = 5 m/s, T h = 700 °C). It is found that the effect of inlet velocity on the temperature performance is quite significant, and the heat transfer coefficient is related to the mass flow rate. The distribution of mass flow rate within the channel casts significant effect on the outlet temperature. The calculated results indicated the effectiveness s (Case1) is 0.72 which is much higher than those of Case2 (0.704) and Case3 (0.574).Yet the second cold plate shows the maximum temperature difference and the pressure drop in all three cases of simulation.