A three dimensional steady numerical analysis has been made for a one unit of single row plate-finned tube heat exchanger located in a uniform flow. The structures of the flow and thermal fields have been examined for conduction-convection conjugate heat transfer problem of the studied fin-and-tube model. The results of the numerical analysis revealed some important effects of geometric parameters on heat transfer from the fin-and-tube surface. The effects of fin thickness, fin pitch, fin length, tube pitch and Reynolds number on Nusselt number, heat transfer rate, fin efficiency and pressure coefficient were examined parametrically. Upstream half of the fin surface yielded a much higher heat transfer coefficient than the downstream half of the fin surface. Especially, the values of fin local heat transfer coefficient is nearly zero in the near region of the tube. As Reynolds number increases, the fin efficiency and the pressure coefficient decrease.