Double-cavity injector

The utility model relates to a double-cavity injector which comprises an injector body, the injector body comprises a first injector and a second injector, the first injector is fixedly connected with the second injector, and the bottom end of the first injector and the bottom end of the second injector are fixedly connected with a first bent pipe and a second bent pipe respectively. During use, the needle head is inserted into a joint, the piston rod on the first injector is pulled to suck joint effusion into the first injector, then the threaded rod is rotated or the pull rod is pulled to enable the rubber column to move upwards until the second branch channel corresponds to the second bent pipe, then the piston rod on the first injector is pushed, and liquid medicine is injected into the joint. The first injector and the second injector are combined for use, so that the injector body is provided with two cavities which can be respectively used for puncturing and extracting liquid and injecting medicine, th