The invention provides a pipe fitting type injection pressurized drainage device. The pipe fitting type injection pressurized drainage device at least comprises an ejecting chamber, a mixing chamber and a pressure expanding chamber; an outlet of the ejecting chamber is communicated with an inlet of the mixing chamber; an outlet of the mixing chamber is communicated with an inlet of the pressure expanding chamber; an outlet of the pressure expanding chamber is connected with a mixed fluid pipeline; an inlet of the ejecting chamber is connected with a high-pressure fluid pipeline; an outlet of the high-pressure fluid pipeline is connected with a throat pipe; the throat pipe is positioned in the ejecting chamber; an outlet of the throat pipe is connected with a spraying nozzle; the inlet at the lower end of the ejecting chamber is also connected with a low-pressure fluid pipeline. When the high-pressure fluid pipeline is connected with the low-pressure fluid pipeline, three-way connection of a conventional pipeline is replaced; the effect of pressurizing a low-pressure ejected fluid is achieved by utilizing an ejecting effect of an ejecting flow formed by accelerating a high-pressure flow in the throat pipe and the spraying nozzle; the flow rate and the operating efficiency of the high-pressure fluid pipeline and the low-pressure fluid pipeline are improved. All parts of the device are spliced by completely adopting standard pipe fittings; the device is easy to manufacture, is not required to be prefabricated in a factory and can be installed and welded in the field, and is convenient to construct.