The utility model discloses a yarn feeding system for an automatic winder. The yarn feeding system comprises an automatic yarn feeding platform, a middle butt joint system, a cop arranging system anda cop storing and lifting system. The automatic yarn throwing platform comprises a support, a three-layer conveying device, a material taking and lifting mechanism and a yarn throwing device, the three layers of conveying devices are respectively an upper-layer platform conveying rail, a lower-layer platform conveying rail and a bottom support recovery conveying rail; the middle butt joint systemis arranged at the starting end of the automatic yarn throwing platform in a matched mode. The cop arranging system and the cop storing and lifting system are arranged on one side of the middle butt joint system in a matched mode and used for arranging cops to be spooled, assembling the cops and the bottom support and conveying the cops and the bottom support to the middle butt joint system. According to the yarn feeding system for the automatic winder, the cop and the bottom support are conveyed through the multiple layers of conveying belts, and the structure is compact; the cop is conveyedfrom the two ends according to the long working position characteristic of the winding machine, and the efficiency is higher; and the system is convenient to pull out for equipment maintenance, and isconvenient to install and maintain.