The printed heat exchanger (PCHE) has the advantages of high efficiency, compact size and low thermal inertia and is considered to be suitable for the supercritical CO2 (SCO2) Brayton cycle. In this work, the thermal-hydraulic performance of a PCHE with rhombic fin channels was experimentally investigated. The combined effects of turbulent intensity and physical property of SCO2 on the PCHE performance were analyzed. Based on the experimental data, an iterative method combined with genetic algorithm (GA) was put forward to derive the heat transfer correlation. The results indicate that the overall heat transfer coefficient of the PCHE is roughly linearly dependent on the Geometric Mean of Peclet numbers of the cold and hot fluids. The iterative method combined with GA is an effective way to obtain the heat transfer correlation of SCO2 in PCHEs with tremendous property variation and limited boundary parameters. The friction coefficient of the SCO2 in PCHE is closely pertinent to the channel structure and the friction coefficient correlations of the cold and hot fluid are often different considering their different channel structure at the inlet and outlet regions. The rhombic fin channel can realize the heat transfer rate per unit volume equivalent to the zigzag channel at the expense of relatively low pressure drops.