A powder sprayer includes a sprayer body having a nozzle head mounted on the top side of the bottle cap thereof, the nozzle head having a transverse mounting hole disposed in communication with a vertical through hole of the bottle cap and a guide notch located on the periphery at one end of the transverse mounting hole, and a spraying mechanism having a nozzle tube positioned in the transverse mounting hole, the nozzle tube having a guide block protruded from the periphery thereof and fitting the guide notch of the nozzle head, an axial air passage and a transverse suction hole disposed in communication between the air passage and the through hole of the bottle cap for sucking powder from the powder bottle through a dip tube into the air passage upon passing of a flow of forced air through the air passage.