Automatic injector

The utility model provides an autoinjector, including casing, syringe subassembly, propulsion subassembly and pressing subassembly, casing includes fixed cylinder and connecting cylinder seat, syringe subassembly is provided in the fixed cylinder, propulsion subassembly includes push rod, push rod retainer and propulsion spring, push rod retainer is provided on connecting cylinder seat, push rod retainer is provided on the connecting cylinder seat. The push rod is provided with a front acting end and a rear connecting end, the propelling spring is arranged at the rear connecting end, the front acting end is used for pressing a piston of the injector assembly, and the rear connecting end is connected to the push rod holder and compresses the propelling spring; the pressing assembly comprises a button, the button is arranged on the connecting cylinder seat, the rear connecting end is separated from the push rod retainer by pressing the button, the push rod moves forwards by utilizing the pushing spring, and the