A flat radiator with flat type heat pipe and its application for portable computers is provided. The heat pipe in a radiator use tubular type and plate type structures. An air convective extended heat exchange surface surrounds and is over against the fan impeller, such that the radiator is extremely compacted, and the heat transport distance in heat pipe is shortened. Further introducing enhanced convective heat transfer structure and setting the fins according to the aerodynamics improve the heat dissipating capacity. The restrictions to a radiator when installing are reduced, which helps to implement the standardization of the radiator series. Also portable computers using the radiator are provided.