A theoretical model that predicts the thermal and fluidic characteristics of a micro cross-flow heat exchanger is developed in this study. The theoretical model is validated by comparing the theoretical solutions with the experimental data from the relative literature. This model describes the interactive effect between the effectiveness and pressure drop in the micro heat exchanger. The analytical results show that the average temperature of the hot and cold side flow significantly affects the heat transfer rate and the pressure drop at the same effectiveness. Different effectiveness has a great influence upon the heat transfer rate and pressure drop. When the micro heat exchanger material is changed from silicon to copper, the thermal conductivity changes from 148 to 400 W/m K. The heat exchanger efficiency is also similar. Therefore, the (1 1 0) orientation silicon based micro heat exchanger made using the MEMS fabrication process is feasible and efficient. Furthermore, the dimensions effect has a great influence upon the relationship between the heat transfer rate and pressure drop. Therefore, the methodology presented in this paper can be used to design a micro cross-flow heat exchanger.