A rapid air discharging rotary valve for a medical air cushion bed. A structure of the rapid air discharging rotary valve comprises a rotary joint (1), a rubber gasket loop (2), an end plate (3), a key head (4), and a joint (5). The end plate (3) is mounted at a lower end of the rotary joint (1). A corresponding groove is fitted between the end plate (3) and the rotary joint (1). The end plate (3) is connected to the joint (5) by using the key head (4). The rubber gasket loop (2) is disposed between the rotary joint (1) and the end plate (3), and the rubber gasket loop (2) provides a good sealing effect. An insertion slot (6) is disposed at the center of the end plate (3). Four holes (11) are machined in the end plate (3). A clamping edge (12) is disposed at a lower portion of each hole (11). An insertion rod (7) is disposed on the joint (5). The insertion rod (7) is connected to an air pump connecting pipe (8). A protruding edge (9) is disposed at one side of an outer rim of an insertion rod end portion (10). The rapid air discharging rotary valve for a medical air cushion bed is easy to mount, ingenious in structural design, low in manufacture cost, and reliable in use.