The invention discloses an automatic separation system for injection product molding. The automatic separation system for injection product molding comprises a separation hopper groove, an upper fixedframe, a separation hopper, a mounting plate and a separation plate; the separation hopper groove is formed in the surface of the upper fixed frame; the separation hopper is embedded in the separation hopper groove; the mounting plate is fixedly connected under the upper fixed frame; the separation plate is vertically arranged in front of the mounting plate; the separation hopper is provided withseparation hopper limiting plates, a feed port, a feed cylinder, a guide hopper body and a discharge port; the separation hopper limiting plates are arranged on four side surfaces of the feed port; the feed port is formed above the feed cylinder; the guide hopper body is fixedly welded under the feed cylinder; and the discharge port is formed under the guide hopper body. Through arrangement of the separation hopper, a traditional injection product molding collecting device can automatically sort injection products, so that the sorting cost is low, and the injection products can be separated into four sorting bags.