The invention relates to an anti-slag flowing slag feeding device for a roller slag cooler. The device comprises a horizontally placed slag feeding cylinder, the upper end of the slag feeding cylinder is provided with a slag inlet, and the left side end opens to form a slag outlet. A screw shaft rotating along with a roller is disposed in the axial direction in the slag feeding cylinder. One end of the screw shaft is in fixed connection with the roller, and the other end extends out of the slag feeding cylinder and is equipped with a bearing seat. The slag outlet side of the slag feeding cylinder is mounted on the end plate of the roller in a plug-in way. The anti-slag flowing slag feeding device for the roller slag cooler provided by the invention can prevent slag flowing phenomenon when circulating fluidized bed boiler hot slag enters the roller slag cooler, can make flow uncontrollable hot slag automatically flowing into the roller slag cooler flow into the roller in a limited and flow controllable way. Once slag flowing phenomenon occurs, the anti-slag flowing slag feeding device with a self-locking function can effectively control the access of hot slag to the roller, prevents slag flowing, and avoids the harm brought about by slag flowing.