The invention provides an automatic sampling device, and the device comprises a sampling gun, a sampling mechanism and a moving mechanism. The sampling gun comprises a sampling bin. The moving mechanism is detachably connected with the sampling mechanism and is used for driving the sampling mechanism to advance along a preset path. The sampling mechanism is detachably connected with the sampling gun, and the driving mechanism is used for driving the sampling gun to move in the direction close to a sampling object under the driving of the moving mechanism, opening the sampling bin, carrying outsampling operation when the sampling gun is inserted into the sampling object by a preset depth, and closing the sampling bin after the sampling operation is completed. Correspondingly, the inventionprovides an automatic sampling method. According to the invention, the sampling mechanism is driven by the moving mechanism to open the sampling bin of the sampling gun and carry out sampling operation, and to close the sampling bin after the sampling operation is completed, so that automatic sampling is realized.