Improving the coupling efficiency of the optical transceiver module in fiber optic gyroscopes (FOGs) benefits both the working efficiency of the module and the signal-to-noise ratio of the FOG system. In this work, a single-mode fiber (SMF) with an elliptical mode field distribution is proposed as the coupling fiber for the FOG transceiver module. The coupling efficiency of the transceiver module using fibers with different mode field distributions at the endface is analyzed. Two structure schemes of the transceiver module are compared: one focuses the beam directly onto the endface of the fiber, and the other collimates the beam and then converge it. The optimal coupling efficiency can reach above 91.5% when the horizontal and vertical mode field radii of the fiber endface are approximately 4.05 μm and 3.37 μm respectively. The influence of the axial and angular alignment errors of the pigtail on the coupling efficiency is also investigated. The maximum tolerance of the axial alignment reaches approximately ±40.10 μm and ±30.08 μm for the two structure schemes. The maximum tolerance of the angular alignment reaches approximately ±4.4° and ±5.2° in the horizontal direction, and approximately ±3.5° and ±3.6° in the vertical direction, respectively. These tolerances are favorable for practical applications.