Gun type needleless injector

The invention relates to the technical field of needleless injectors, in particular to a gun type needleless injector. The gun type needleless injector comprises a gun body, a driving piston assembly,an energy storage mechanism, an inner hydraulic pipe, an outer hydraulic pipe, an energy storage mechanism, an injection one-way valve and an oil storage barrel. According to the gun type needlelessinjector, a piston pushes a hydraulic rod by the pneumatic piston when in percussion, the hydraulic rod drives the hydraulic piston to push hydraulic oil in a first oil cavity forwards to enter a second oil cavity, a stepping piston in the outer hydraulic pipe is forced to drive a push rod to conduct percussion forwards, and therefore the push rod pushes out liquid medicine in a medicine core at the head end of the outer hydraulic pipe at a high speed, single quantitative injection is completed, when the hydraulic piston retreats, the hydraulic oil in an oil storage barrel can be automaticallysupplemented into the firs