To provide a cooling method and a cooling system by which water cooling is performed at low cost by diverting a present water-cooling equipment for wide flange beams without generating bends and a camber even when the size of a T-shape steel is varied.

This cooling system is provided with a pair of side guides 14 which are installed on both sides of the pass line on the conveying route of the T-shape steel 12 and moved in approaching and separating direction each other, a web supporting roller 13 which is built in the side guides 14 and with which the web 12a of the T-shape steel 12 is supported approximately horizontally, cooling nozzles 16a, 16b which are provided above and beneath the web 12a of the T-shape steel 12 along the pass line and with which the inside of the flange 12b of the T-shape steel 12 is cooled and a cooling nozzle 15b which is provided in a position facing the outside of the flange 12b of the T-shape steel 12 along the pass line and with which the outside of the flange 12b is cooled. The outside of the flange or the inside and the outside of the flange are water-cooled while keeping the web 12a of the T-shape steel 12 approximately horizontal and moving the T-shape steel in the longitudinal direction by using the cooling system 11.