Single mode polarization-maintaining fibers are widely used for its excellent polarization-maintaining property. In the field of precision measurement of cold atoms, in order to realize the reasonable distribution of laser power, lasers are guided with fibers into different experiment platforms in the process of optical path building. Poor laser polarization matching at the fiber incident end can cause severe jitter of output laser power. Taking the 397 nm laser as an example, it’s introduced how to match the polarization direction of linearly polarized laser in space with the birefringence axis of polarization-maintaining fiber. A polarizer is placed at the fiber output end, and laser power jitter out of the fiber can be controlled at about 5% by rotating the polarizer.