Identifying, monitoring, and locating the loss of bolt preload for bolted steel members in corrosive conditions is difficult. Hence, this study investigates the strain distribution on the surface of the cover plate of bolted member based on optical frequency domain reflectance (OFDR) technology. Fiber optic calibration tests, corrosion tests of bolted steel members, and numerical simulations using ANSYS software are conducted. The test and numerical simulation results show that when the bolt preload is 100 kN, a preload loss exceeding 10% in the identified bolt can be accurately detected and localized. Using the longitudinal pasting method, and excluding errors from the fiber optic paste tip effect, a comparative analysis is performed on the distributed optical fiber strain loss rate before and after corrosion. The results show strain loss rates of 10.6%, 16.7%, and 28.1%. Additionally, the strain distribution patterns from the test and simulation results coincide, demonstrating that OFDR technology can be used to identify and localize bolt preload loss in bolted specimens under corrosive conditions.