The invention discloses a blow-down gust wind tunnel with drainage sections. The blow-down gust wind tunnel comprises a power section, a diversion section, a diffuser section, the drainage sections, asettling and contraction section, a test section and an exit diffuser section. The drainage sections have two types, one refers to a throttle-valve type with moving vanes and the other refers to a drainage structure with multiple fan sections. One end of the power section is communicated to the external while the other end of the power section is connected with the diversion section, the other end of the diversion section is connected with the diffuser section, the diffuser section is communicated with the settling and contraction section, a honeycomb and a damping mesh are arranged at the junction of the diffuser section and the settling and contraction section, the other end of the settling and contraction section is connected with the test section, the other end of the test section isconnected with the exit diffuser section communicated to the external, and one ends of the drainage sections are connected with the diversion section while the other ends of the drainage section are communicated with the external. The gust wind tunnel can generate gust in high or low frequency.