A air shroud for dissipating heat from an electronic component is composed of a air shroud of a roughly U-shaped cross section, whose left and right sides are formed into a first and a second opening, respectively. A passage is formed between the first and second openings, enabling air to flow along a specific direction. A flexible thin piece is fixed inside the air shroud which covers a specific electronic component on a circuit board, and the flexible thin piece is touched with a surface of the electronic component. The fast-flowing air flows quickly along the passage, so as to effectively cool down a working temperature of the specific electronic component, thereby increasing a lifetime of usage of the specific electronic component.