The invention discloses a multifunctional pressure/flow control valve with a good sealing property. The multifunctional pressure/flow control valve is applied to a high-pressure standby steam source of a water supply pump steam turbine and comprises a valve, a hydraulic executing mechanism and a support frame which connects the valve with the hydraulic executing mechanism. The valve comprises a valve body, a valve seat, a sleeve and a valve rod, wherein the valve seat and the sleeve are mounted in the valve body and sequentially connected. A plurality of screening holes are designed on the portion, communicating with an inlet of the valve body and the valve seat, of the sleeve. The sleeve is matched with a valve plug mounted at the end of the valve rod. The valve rod extends out of the valve body and is connected with the hydraulic executing mechanism for providing driving force. The hydraulic executing mechanism comprises an oil cylinder-piston assembly and a hydraulic control module. A hydraulic control one-way valve and a cartridge valve communicate with a security oil pipeline through a pressure relief one-way valve. According to the multifunctional pressure/flow control valve, the functions of opening, closing, rapid closing, adjusting, lock-up and the like of the valve can be achieved, and the multiple functions are integrated to a valve control system, so that the system structure is simplified, the maintenance difficulty is lowered, and meanwhile, the production and maintenance cost is also greatly reduced.