Quick injection gun

The invention discloses a rapid injection gun which comprises a gun body, wherein an injector is installed at the top end of the gun body, a replacement assembly is arranged at the position, located at an output end of the injector, of the end of the gun body, and the replacement assembly is composed of an adjusting mechanism and a limiting mechanism; and the adjusting mechanism comprises a poke rod, a bottom rod and a replacement trigger, the poke rod is rotatably connected with the end adjacent to the bottom rod, the other end of the bottom rod is rotatably connected with the surface of thereplacement trigger, the other end of the poke rod is arranged at the output end of the injector in a sleeving mode, and the top end of the replacement trigger is rotatably installed on the surface ofthe inner side of the gun body. By means of the designed replacement assembly, a needle head can be rapidly taken down, operation is very easy and convenient, the needle head can be rapidly installedby being matched with a de