The invention discloses an automatic door opening device and a flexible endoscope cleaning and disinfecting device and belongs to the technical field of medical cleaning and disinfecting equipment. The automatic door opening device comprises a disinfecting device body (1) and a sealing door (3) above the disinfecting device body (1). The automatic door opening device is characterized in that a reset unit and a locking mechanism are arranged between the disinfecting device body (1) and the sealing door (3), the reset unit is used for enabling the sealing door (3) to keep open, the locking mechanism is used for locking the sealing door (3) when the sealing door (3) is closed, a pedal mechanism is arranged on the lower portion of the disinfecting device body (1), and the pedal mechanism is connected with the locking mechanism and drives the locking mechanism to conduct opening or locking. The locking mechanism of the automatic door opening device locks the sealing door, the sealing performance of the closed sealing door is guaranteed, the pedal mechanism enables the sealing door to be opened in a stamped mode, and there is no need to touch the sealing door by hand; the sealing door of the flexible endoscope cleaning and disinfecting device can seal a disinfecting tank, and therefore no water flows out in the whole cleaning process.