Distributed optical fiber sensors have been intensively used to measure the strain, temperature, displacement, and pressure of long-distance, large-span, and super high-rise structures with long term and high precision, due to the unique advantages of high sensitivity, anti-corrosion, immune to electromagnetic interference, absolute measurement, small size and light weight. When the host material is steel structures, optical fiber sensors have often been attached on the surface. For the different properties of silica fiber and steel material, obvious interfacial feature exists. The interfacial debonding often occurs between the surface-attached sensors and the monitored structures during the measurement. To guarantee the effective and accurate measurement, study on the occurrence and propagation of interfacial debonding should be performed. For this reason, strain transfer theory is adopted to discuss the interfacial interaction between the sensor and the structure and the influence of interfacial debonding on measurement. Experiments have been conducted to validate the effectiveness of the theoretical model. The close-form equation of interfacial shear stress with the non-uniform constraint considered has been given, and sensitivity of the correlated physical parameters has been discussed, suggestions are proposed for the design of distributed optical fiber sensors in practical engineering.