In order to provide references for the optimal design of radiator and operation of direct air-cooled condenser, the flow and heat transfer characteristics in fin channel are investigated by CFD simulation in this paper. The effects of face velocity and ambient temperature on heat transfer coefficient and pressure drop are discussed, of which the correlative expression are fitted. It is shown that both heat exchanger coefficient and pressure drop increase with the increase of the face velocity, and the ambient temperature has significant effect on heat dissipation capacity of the air-cooled cell. The results obtained are helpful for the design and operation of air-cooled system.