The invention relates to a cord fastener. The cord fastener is composed of a cord groove 1, a cord penetration hole 2, a cord pressing plate 3, a plate groove 4 and a special-shaped spring 5 which areintegrated. When the cord fastener is used for knots of a waistband of sport pants or a shoelace, two ends of each cord to be tied penetrate through the cord penetration hole, and then two cords which penetrate through the cord penetration hole are tightly pulled and wind into the cord groove on the outer side of the cord penetration hole for one or two circles; the cord pressing plate is arranged in the cord groove, the cord pressing plate is applied with elastic force of the special-shaped spring and can only move to the cord groove in the plate groove, accordingly, the cords which wind into the cord groove are instantly pressed by the cord pressing plate and cannot be separated from the cord groove, the cords which penetrate through the cord penetration hole are fixed, and the draggingforce required by manual knot tying is achieved. Two ends of each cord are fixed by the cord fastener, and the sport pants or shoes cannot be separated from the human body. The cord fastener is easyto operate, practical, efficient, and low in cost, and the traditional manual knot tying trouble brought to people is avoided.