The invention discloses a device for spraying a powder drug. The device comprises an air blower (1), wherein a handle (2) convenient for grasping is arranged on a case; the air inlet of the rack (1) is connected with a container (4) used for holding the powder drug through a section of short pipe (3); an air outlet is connected with a long pipe (5); when the air blower works, the powder drug is ejected from the long pipe; the container used for holding the powder drug is a small barrel; a through hole is formed in the bottom of the barrel; a pipe thread (8) penetrates through the hole and is matched with a pipe screw nut to be fixed at the bottom wall of the barrel; the lower section of the pipe thread is matched with the threaded part of a T-shaped pipe (11); the outer wall of the other part of the T-shaped pipe is matched with one end of the short pipe connected with the air inlet in a fastening manner; a guiding pipe (12) is accommodated in the central hole of the pipe thread; a plurality of holes are formed in the wall of the guiding pipe. According to the invention, powder such as frozen powder and fresh lime powder which contain formaldehyde can be sprayed, the spraying speed is high, the effect is good, silkworms can be sprayed all over, and the device is beneficial to silkworm breeding health.