An automatic pet feeder includes a food container, a feeder body, and a bottom shell in sequence from top to bottom. A food-container bottom shell in communication with the food container is arranged at a bottom of the food container, and a bottom of the food-container bottom shell is a food supply passage having a gradually narrowing opening. A food releasing assembly is arranged on a side of the food supply passage, and a sliding passage for reciprocating movement of the food releasing assembly is arranged on a sidewall of the food-container bottom shell. A feeder main shell is arranged below the food supply passage, and a food exit assembly is arranged inside the feeder main shell. The food exit assembly includes a food pushing member matching with a food outlet and configured to move in a reciprocating manner below the food supply passage.