Wedge angle (the angle between the two sides of the V belt), the strength layer consists of a multi-layer rubberized cord or a single row of dipped cord. The ratio of the width of the top surface to the height of the belt is 1.1~1.2, and the bandwidth is reduced by about 1/3 compared with the ordinary V-belt, so the lateral rigidity is large. The top of the belt is arched so that the rope core remains aligned when the force is applied, so that the force is even and the role of each rope is fully exerted. The strength layer rope is discharged at a slightly higher position, and the belt has a concave shape on both sides, and a layer of oriented fiber film is disposed between the strength layer and the compression layer. Due to the structural characteristics, the transmission capacity can be increased by 0.5 to 1.5 times than the ordinary V-belt at the same speed. When the transmission power is the same, the structure size of the narrow V-belt is reduced by 50% compared with the ordinary V-belt, the service life is obviously extended, the limit speed can reach 40~50m/s, and the transmission efficiency can reach 90%~97%. In addition, the use of a narrow V-belt can shorten the transmission center distance and reduce the pulley width, which is widely used for various power transmission.