Quarter-wave plate is a key component in fiber current sensing system. A quarter-wave plate fabricating technique is proposed and demonstrated. The two sections of high-birefringence fibers (HBF) with approximately equal length are orthogonally fused and the angle between their fast axes is 90°. Stretching one of two fibers can adjust the phase difference between the two fibers to be π/2 precisely. A high-birefringent fiber loop mirror (Hi-Bi FLM) is realized by the two fibers fused to 3 dB coupler and the phase difference is determined by real-time detection of the transmissivity of the Hi-Bi FLM. The transmissivity function of the Hi-Bi FLM is deduced and the variation of the transmissivity is analyzed in detail. The phase difference is confirmed experimentally based on the transmissivity curve and its slope. The fabricating technique which has been achieved experimentally, and has excellent features, such as high accuracy and convenient operation.