The invention discloses a portable small-tension yarn winding machine for a large-core-number high-density micro-cluster optical cable, wherein the machine comprises a rack, a motor, a supporting sleeve, a central hollow pipe, a first bearing, a movable ring mold seat, a yarn drum shaft sleeve, a guide mold, a flying shuttle and a yarn guide pipe; the central hollow pipe is rotatably mounted on the inner side of the supporting sleeve through the first bearing; the motor is connected with the first end of the central hollow pipe through a transmission mechanism, the movable ring mold seat is mounted at the second end of the central hollow pipe, and the guide mold is mounted on the movable ring mold seat; the yarn drum shaft sleeve is rotatably mounted on the outer side of the supporting sleeve through a second bearing; the flying shuttle is fixedly mounted on the movable ring mold seat; and the yarn guide tube is fixedly arranged on the flying shuttle. The rotating resistance torque of the second bearing can be converted into the product of yarn winding tension and the force arm from the outer diameter of a yarn roll to the central hollow pipe, the maximum yarn winding tension is small, the maximum value and the minimum value of the yarn winding force value are controllable, control is safe, the situation that a micro-cluster pipe or an optical fiber is damaged by tying cannot occur, and the yarn winding machine is reliable.