The invention discloses a pesticide sprayer for trees. The sprayer includes a frame body, a lifting device, a pushing device, a pushing arm and a water tank, wherein the top of the water tank is provided with a blending chamber, a rotary pin shaft extending upwards and downwards is arranged inside the blending chamber, the outer wall of the rotary pin shaft is correspondingly provided with two blades on the left and right sides, and the inner top portion of the water tank is provided with a containing cavity, a stud extending upwards and downwards is arranged inside the containing cavity, and a stop dog is installed between the top portion of the containing cavity and the bottom of the blending chamber; the middle end of the inner portion of the stop dog is provided with a first motor, and the top portion of the first motor is connected with the extending end of the bottom of the rotary pin shaft; the bottom of the first motor is connected to the extending end of the top portion of the stud, and through holes are correspondingly formed inside the parts, positioned on the left and right sides of the first motor, of the stop dog; the top portion of each through hole is provided with a first concave part, the side, away from the first motor, of each through hole is provided with a sliding groove, and each sliding groove is internally connected to a sliding block in a sliding fit mode, wherein the inner wall of the side, away from the corresponding through hole, of each sliding groove is provided with a transverse push device.