Connecting device for powder weighing system and powder weighing system

The utility model discloses a connecting device for a powder weighing system and the powder weighing system, and the connecting device comprises a flexible dustproof part which sleeves the outer side of a first connecting pipe and the outer side of a second connecting pipe and is connected with the first connecting pipe and the second connecting pipe; the material passing part comprises a material passing pipe and an elastic part, a limiting boss is arranged on the periphery of the material passing pipe, the material passing pipe is sleeved with the elastic part, the upper end of the elastic part is matched with the limiting boss, and the lower end of the elastic part is suitable for being matched with the first connecting pipe so that the material passing pipe can be installed in the first connecting pipe; the material passing part is configured to drive the material passing pipe to move in the direction close to the second connecting pipe when materials enter the material passing pipe, and a part of the mat