Current multi-channel laser ranging technologies applied in accelerator alignment suffer from high equipment costs and complex system deployment. To solve these problems, this paper proposes a frequency-sweeping laser interferometric ranging technique adopting spherical collimators. A frequency sweeping laser interferometric ranging system integrated with HCN (H13C1?N) gas absorption cells, optical switches and spherical collimators was constructed to realize high-precision absolute distance measurement over a large range. A spherical collimator compatible with the target base of corner reflectors for laser trackers was designed, which reduces equipment costs while ensuring the required measurement accuracy. System performance tests were performed in an experimental environment simulating accelerator alignment. The results show that within the measurement range of 30 m, the ranging error of the proposed system is not more than 30 μm, fully satisfying the requirements of accelerator alignment. This system provides a high-precision and highly adaptable solution for accelerator alignment, and possesses great practical value in engineering applications.