Knapsack sprayer

The invention discloses a knapsack sprayer. The knapsack sprayer comprises a water storage barrel, a water pump, a handle manipulator, a battery supply and a control system, wherein the water storage barrel is connected with the water pump through a water conveying pipe, the water pump is connected with the handle manipulator through a water diversion pipe, a spray nozzle is arranged at the end part of the handle manipulator and arranged on the inner side of an air outlet end of an air supply barrel, and an air supply motor is arranged on the inner side of an air inlet end of the air supply barrel, electrically connected with a switch and axially connected with a blowing fan; the battery supply is electrically connected with the water pump, the air supply motor and the control system respectively, and the switch for controlling the water pump and the air supply motor is arranged on the handle manipulator; when the switch is turned on, the water pump and the air supply motor work simultaneously, and outside ai