The invention discloses a building wind energy use system, and relates to the field of wind energy use devices. The size of blades is reduced, meanwhile, the wind of the position of the small blade isimproved, and wind energy use is ensured. A wind power amplification mechanism carries out amplification through a flow guide cover of a conical structure, upper and lower suction force of an upper reinforcing pipe and a lower reinforcing pipe is used for reinforcing the inner airflow flowing, the wind energy conversion use is reinforced, and the wind energy use effect is ensured. The angle can be subjected to fine adjustment, wind energy use is ensured, the lower reinforcing pipe is of a flexible structure, and can well adapt angle rotation, the lower reinforcing pipe is downwards connectedto a building vertical ventilation pipe, the airflow upward suction force can be effectively reinforced, and the blade rotation effect is improved. An auxiliary supporting column and a supporting platform are arranged, stability of the device in the high altitude can be effectively ensured, the device can be prevented from being blown down through large wind, and the life safety is prevented frombeing endangered.