Pressure-adjustable needleless injector

The pressure-adjustable needleless injector comprises a main body, the needle-free injection ampoule bottle is arranged in one end of the main body through threaded connection; a punch rod is arranged in the main body in a sliding manner relative to the needleless injection ampoule bottle; a first spring is arranged between the punching rod and the main body; a clamping block is arranged at one end, close to the needleless injection ampoule bottle, of the punching rod; the sliding plate is slidably arranged in one side of the main body; a second spring is arranged between one end of the sliding plate and the main body; a firing key is arranged on the outer side of the main body in an inward sliding manner; the main body is internally provided with a plurality of limiting keys in a sliding manner on one side of the percussion key; the sliding plate is provided with a reset groove opposite to the percussion key; a limiting clamping groove is formed in the sliding plate relative to the limiting key; one end of t