The utility model discloses a power sprayer provided with a water flow control button. The power sprayer comprises a water box, wherein a control box is arranged below the water box, a motor, a storage battery and a frequency changer are arranged inside the control box, the motor is connected with a water pump, and the water pump is in sealed connection with the bottom of the box body through a water inlet pipe. The water pump is connected with a spraying pipe through a water outlet pipe, a spraying head is arranged at the front end of the spraying pipe, a control switch is arranged on the spraying pipe, and the motor, the storage battery and the control switch are respectively connected to the frequency changer. When an operator uses the power sprayer, the operator can change output frequencies of the frequency changer by adjusting the control button according to the quantity of drug needs of different periods of peanuts, then change the working frequency of the motor, and therefore change the drug outlet quantity. The power sprayer ensures the drug quantity required by the peanuts and meanwhile ensures that the drugs are not wasted.