A cable tie comprising: a strip-like flexible body having a first surface and a second surface being opposite to each other, the first surface being provided with a plurality of equidistantly arranged ribs; and a fastening slot being provided at a first end of the flexible body and having a third surface and a fourth surface being opposite to each other, the third surface being adjacent to the first surface, the fourth surface being distant from the second surface, and the third surface and the fourth surface each being formed with an opening (121a, 122a) to allow a second end of the flexible body to pass through the fastening slot; wherein the fastening slot is formed with an engaging portion for engaging the ribs of the flexible body when the flexible body passes through the fastening slot; and the engaging portion is located between the third surface and the fourth surface and extends toward the opening of the fourth surface, the engaging portion has a fixed end adjoining the third surface and a free end facing the opening of the fourth surface, the engaging portion is further provided with a first engaging tooth, and the distance between the tip of the first engaging tooth and the fixed end along the lengthwise direction of the flexible body is smaller than the distance between the free end and the fixed end along the lengthwise direction of the flexible body characterized in that the distance between the base of the ribs and the second surface of the strip-like flexible body is smaller than the width of the openings of the fastening slot such that the part of the tip of the first engaging tooth with which the ribs of the flexible body are contacted is smaller than the part of the free end with which the ribs of the flexible body are contacted when the flexible body passes through the fastening slot. a strip-like flexible body having a first surface and a second surface being opposite to each other, the first surface being provided with a plurality of equidistantly arranged ribs; and a fastening slot being provided at a first end of the flexible body and having a third surface and a fourth surface being opposite to each other, the third surface being adjacent to the first surface, the fourth surface being distant from the second surface, and the third surface and the fourth surface each being formed with an opening (121a, 122a) to allow a second end of the flexible body to pass through the fastening slot; wherein the fastening slot is formed with an engaging portion for engaging the ribs of the flexible body when the flexible body passes through the fastening slot; and the engaging portion is located between the third surface and the fourth surface and extends toward the opening of the fourth surface, the engaging portion has a fixed end adjoining the third surface and a free end facing the opening of the fourth surface, the engaging portion is further provided with a first engaging tooth, and the distance between the tip of the first engaging tooth and the fixed end along the lengthwise direction of the flexible body is smaller than the distance between the free end and the fixed end along the lengthwise direction of the flexible body characterized in that the distance between the base of the ribs and the second surface of the strip-like flexible body is smaller than the width of the openings of the fastening slot such that the part of the tip of the first engaging tooth with which the ribs of the flexible body are contacted is smaller than the part of the free end with which the ribs of the flexible body are contacted when the flexible body passes through the fastening slot.