The invention discloses an automatic garbage classifying system and method and belongs to the technical field of garbage classification. The system comprises a rack, a garbage can, a trigger, a camera, a central processing unit, a sliding track, a classifying executor, a garbage receiving platform and a laser scanner, wherein the trigger, the camera, the central processing unit, the sliding track,the classifying executor and the garbage receiving platform are installed on the rack, and the laser scanner is installed on the sliding track. The laser scanner is connected with the sliding track in a sliding manner. The central processing unit is connected with the trigger, the camera, the classifying executor, the garbage receiving platform and the laser scanner and controls the trigger, thecamera, the classifying executor, the garbage receiving platform and the laser scanner to operate. According to the system and the method, the manner of combining an image and three-dimensional pointcloud is used for scanning garbage to obtain the colorful outline, and high-accuracy automatic classification is carried out. The garbage can be classified into multiple types according to the situation, and only the classifying executor and the garbage can need to be increased. The system can recognize substances with sparks and carry out spraying directly, and the situation that a fire source enters the garbage can is eradicated.