Abstract: Polarization-maintaining fiber coupler（PMC）is widely used in military and commercial applications．However，the bandwidth of the ordinary PMC is very narrow and it could meet the requirements of the various light sources．To solve this problem，a broadband PMC shall be developed．Based on the electromagnetic theory of fibers and the principles of the fused bi-conical taper polarization-maintaining fiber couplers（FBTPMC），the tapefused process was improved．The fabrication of improved FBTPMC was realized based on years of production experience and experimental results.Meanwhile, the measurement results show that the bandwidth parameters of the products could meet the requirements of various light sources.