This study develops a force-measurement method based on distributed optical fiber strain sensing. A thin-walled ring loading test with the fiber Bragg grating (FBG) and Brillouin optical time domain analysis (BOTDA) techniques is performed. The principles of fiber optic sensing, data fitting, and error analysis are also introduced in detail. The results obtained by FBG and BOTDA are compared and analyzed in the experiment to further verify the feasibility of proposed method. The experimental results show that the load value calculated by the BOTDA data is closer to the actual one. Furthermore, the distributed fiber optical monitoring technology has been proven to meet the accuracy requirements of data acquisition in geotechnical tests.