Using the theory that the coupling ratio of fiber coupler changes periodically with center distance of two optical fibers, in the fabrication process of fiber coupler, the fiber is fused but not stretched when light begin to split. The reduction of diameter of fiber is dependent of the theological characteristic of the fused fiberglass, and the light continues to split. A new manufacturing method of optical fiber couplers is developed with fused biconical taper experimental system. The tested results show that the performance of the novel optical fiber coupler complies with the performance indexes of fused biconical taper coupler, and its diameter of coupling region is double of classical fused biconical taper coupler.