The invention aims to solve the problem that existing injectors cannot inject three different medicines separately and discloses a device for sandwich injection. The device comprises a mounting plate,a
flat mirror, a universal rod, an outer casing, a push rod, a small storage battery, a lead, a
guide tube, a telescopic
airbag, an air guide plate, a mounting rod, a connecting rod, a heating rod, an injection head, a first gear, a first rotating shaft, an inner
barrel, a liquid passing hole, a second gear, a second rotating shaft, a chain, a motor, a
rubber membrane, a guide
barrel, a
coil spring, a press plate, a sliding rod, a
lantern ring and a rubber
gasket. The structures of three chambers of the inner
barrel are ingeniously combined, so that separate storage of three different medicines can be realized, meanwhile, injection of three different medicines is facilitated, use of three injectors is avoided, all that is required for injection of different liquid medicines through switching of the inner barrel is to perform injection sequentially by the injection heads of the injectors, and the device is more convenient to operate, meets social demands and is worth promoting in the medical field.