Abstract: On the base of structure features of plain fin rectangular channels,a coupled calculation model of flow field and temperature field was established.One computational fluid dynamics(CFD) program had been used for the simulation on the fluid flow and heat transfer in the physical model.Graphics and trends of temperature,pressure,velocity and local heat transfer coefficients of multiple cross-sections were given and analysed.The performance of intercooling heat exchanger under different loads had been studied.The results could be a useful reference for the optimum design of marine gas turbine intercooling heat exchanger.