The invention relates to a liquid storage tank pressurized urea solution metering injection system for a diesel vehicle, which comprises a liquid storage tank, an injector, an air storage tank, a first electromagnetic valve, a second electromagnetic valve, a Venturi pipe, a mixer and a control device, wherein the mixer comprises an inlet and an outlet which is opposite to the inlet and is communicated with the inlet, the injector is installed in the side wall of the mixer, the air storage tank is respectively in air-path connection with the second electromagnetic valve and the liquid storage tank through the first electromagnetic valve, the liquid storage tank is communicated with liquid in the injector, the second electromagnetic valve is in air-path connection with the Venturi pipe, the Venturi pipe is in air-path communication with the inlet of the mixer, the control device is electrically connected with the first electromagnetic valve, the second electromagnetic valve and the injector, and preferably, the liquid storage tank pressurized urea solution metering injection system also comprises safety control parts including a primary pressure reducing valve, a secondary pressure reducing valve, a liquid level sensor, a first temperature sensor, a first pressure sensor, and the like. The liquid storage tank pressurized urea solution metering injection system has artful design, simple structure, low cost, good reliability, safety and energy saving, is convenient to integrate into diesel engine tail gas post treatment, and is suitable for large-scale popularization and application.