The utility model discloses a packaging box which comprises a box body (3) and a movable plate (4). The movable plate (4) is arranged inside the box body (3) and divides the same into an upper cavity (2) and a lower cavity (5), the movable plate (4) is enabled to fit with the inner wall of the box body (3) to block air flow between the upper cavity (2) and the lower cavity (5), the movable plate (4) can slide along the inner wall of the box body according to pressure difference between the lower cavity (5) and the upper cavity (2), ventilation holes (7) are arranged at the bottom of the lower cavity (5) and communicated with the air, a suction hole (1) is arranged on the upper portion of the upper cavity (2), and a one-way valve (6) is arranged in the suction hole (1). Liquid left at the bottom of the box can be sucked clean without a suction pipe or a spoon, so that waste is reduced, and environmental pollution is avoided; the packaging box is simple in structure and convenient to use.