The invention discloses a high-speed gearbox matched with a high-speed fan for use. The high-speed gearbox comprises a box body, a low-speed shaft, a high-speed shaft, a low-speed gear and a high-speed gear. The high-speed gear and the low-speed gear are in engaging transmission through a single helical gear. The low-speed gear is mounted on the low-speed shaft. The high-speed gear is mounted on the high-speed shaft. The high-speed shaft and the low-speed shaft are mounted on a bearing bush of the box body. The high-speed gear and the low-speed gear are engaged mutually. Thrust plates are arranged on the two sides of the high-speed gear. The low-speed gear is clamped between the thrust plates when the two thrust plates operate. A lubricating system of the gearbox adopts a main oil pump and an auxiliary oil pump which are used in a matched mode, the lubricating effect and safety operation of the system are ensured, the gears in the gearbox are of a single helical gear structure, the thrust plate structures are arranged on the two sides of the high-speed shaft so to transfer loads and bearing external axial force, and force on the high-speed shaft of an impeller can be transferred to the low-speed shaft; and the structure is low in noise, and transmission is stable .