Abstract: Conjugated heat transfer performance in a countercurrent micro-channel heat exchanger was analyzed and simulated by using the one dimensional gas convection and wall axial heat conduction model. The effects of structural parameters, operating conditions and heat conductivity of wall material on the performance of heat transfer of this micro-channel heat exchanger were investigated. The simulation results indicated that the properties of micro-channel heat exchanger were much different from those of conventional heat exchanger due to the synergetic effect of radial and axial heat conduction in the micro-channel heat exchanger.Low conductivity metal, such as stainless steel, is an excellent wall material and available for micro-channel heat exchanger. There existed an optimal operation flux, which could be used as a standard flux for a given micro-channel heat exchanger, and micro-channel heat exchanger was not suitable when the operation flux was lower than the standard flux. The maximum heat transfer efficiency of micro-channel heat exchanger decreased with increasing operating flux. The calculation results also showed that micro-channel heat exchanger with high aspect ratio channel and optimal wall width had higher efficiency than other configurations.