The invention relates to an air outlet mechanism and an air treatment device. The air treatment device is provided with a vertical air duct, and the first upper end surface of the air duct is inclined; the air outlet mechanism comprises a first air outlet plate and a second air outlet plate, the first air outlet plate surrounds the higher side of the first upper end surface and is rotationally connected with the air treatment device, and the second air outlet plate surrounds the other parts of the first upper end surface and is connected with air treatment device; and the first air outlet plate includes a straight plate rotationally connected with the air treatment device and a curved plate connected with the straight plate, the second air outlet plate is inclined toward the outer side ofthe air duct in the direction away from the first upper end surface, an air outlet is formed between the first air outlet plate and the second air outlet plate, and the first air outlet plate can be rotated to adjust the air outlet. The first air outlet plate can be rotated to adjust the shape, size and air outlet direction of the air outlet, the air outlet flexibility and controllability are increased, control is facilitated, the satisfactory air supply volume and air pressure effect are achieved, and the air supply dead angles are eliminated; and the air outlet mechanism is high in integrity, convenient to produce and simple in assembly.