Abstract: The present invention discloses a multifunctional negative pressure drainage system switchable between various modes, including continuous negative pressure, intermittent negative pressure, rinsing, drug administration, and drug administration loop, including a medical wound dressing, a waste fluid bottle, a vacuum pump, a draining tube A, an airway A, a draining tube B, a peristaltic pump, a draining tube C, an infusion bottle, a draining tube E, a control valve A, a control valve B, and a control valve F. The medical wound dressing, the draining tube B, the peristaltic pump, the draining tube C, and the infusion bottle are connected in turn. The medical wound dressing, the draining tube A, the waste fluid bottle, the airway A, and the vacuum pump are connected in turn. The draining tube E is connected between the draining tube C and the draining tube A. The control valve A is disposed on the draining tube A.