The invention relates to a jet flow pressure regulating device of a water injection well. The jet flow pressure regulating device is characterized by comprising a pump body, a high-pressure nozzle, a mixed pressure water outlet pipe, a low-pressure water inlet pipe, a high-pressure water inlet pipe and a control system, wherein the pump body is cylindrical and is internally provided with a channel communicated with the mixed pressure water outlet pipe; the lower part of the channel is provided with a tapered semi-spherical liquid inlet cavity; the middle of the channel is provided with a choke; the upper part of the channel is provided with a gradual expanding buffer cavity; the top of the buffer cavity is axially connected with the mixed pressure water outlet pipe; the liquid inlet cavity is radially communicated with the low-pressure water inlet pipe; the high-pressure nozzle is of a hollow cylinder shape; the upper part of the high-pressure nozzle is matched with the liquid inlet cavity to be provided with a tapered liquid spraying hole; the lower part of the high-pressure nozzle is connected with the liquid inlet cavity; the bottom of the high-pressure nozzle is connected with a high-pressure water inlet pipe; and the mixed pressure water outlet pipe, the high-pressure water inlet pipe and the low-pressure water inlet pipe are respectively provided with a pressure regulating valve and a sensor, and each pressure regulating valve and each sensor are respectively connected with a control system through leads. The jet flow pressure regulating device is capable of accurately regulating water injection pressure, is reduced in energy consumption, and can be widely applied to a water injection pressure regulating process of various offshore platform injection wells.