Based on the assumption of locally fully developed flow and slip-fiow theory, we preseota method to simulate the heat transfer and momentum exchange of gas with a solid surfacein micro-channels, and the method was proved by comparing with Pfahler’s exprimentalresults. Effect of the gas compressiblity and slip-flow on the skin friction was discussed indetail, the result demonstrates that Knudsen number should be considered in the analysisof flow in micro-domains. In the second part, the temperaturedump theory was studiedto explain the abnormal phenomina which is different from that of macro-scale channels.Some important conclusions of momentum and heat transports in microscale channels wereobtained.