The invention relates to a multifunctional water needle knife. The multifunctional water needle knife includes a blade needle knife part and a sleeve pipe needle knife part; the blade needle knife part is used for point fixing, positioning, separation and stabbing; the sleeve pipe needle knife part is composed of a round-head needle body and a round-head needle core, the round-head needle body ishollow and includes a hollow needle body unit and a round-head needle pin which are connected in sequence, liquid holes are formed in the two side walls of the round-head needle body, a triangle valveconnected with an injection catheter is arranged on the tail portion of the hollow needle body unit, a valve port is connected with an injection apparatus and a negative-pressure suction device, andthe round-head needle body is used for drug injection or suction washing; and the round-head needle core comprises a needle knife handle, a hand-held unit, a needle knife body and a needle pin unit, is arranged inside the round-head needle body and can close the liquid holes in the round-head needle body. The multifunctional water needle knife has the advantages that needle knife release surgerieson joints, nerve roots, muscular fasciae and the like can be achieved, namely blunt release, focus clearance, clogged-part dredging, drug irrigation, local anesthesia and the like are achieved, patient's pain, operation difficulty and tissue damage are reduced, operation is convenient, and the safety is high.