The utility model discloses a spray gun with an automatic gun opening and closing function, which comprises a spray gun body, a powder flow channel is arranged in one end of the spray gun body, a venturi throat pipe is arranged in the other end of the spray gun body, and the input end of the venturi throat pipe is communicated with the tail end of the powder flow channel; and an air input channelis formed in the upper end of the spray gun body. The utility model discloses a spray gun with an automatic gun opening and closing function. Signals detected by the displacement sensor are transmitted to the controller to be processed and analyzed, then the butterfly valve and the air compressor are controlled to work, and when the powder room moves, the butterfly valve is opened, the powder roomstops moving and the butterfly valve is closed, it is guaranteed that the powder room and the butterfly valve can work synchronously, powder waste is avoided, and the product quality and percent of pass are improved.