Based on the optical frequency domain reflection technology, we establish a strain transfer model, derive the strain transfer relationship of fiber, and analyze the influencing factors of the distributed fiber strain measurement results. Through the equal-strength beam bending experiment, we study the measurement results of the fiber-optic sensor from the aspects of the adhesion length and the shear modulus of the coating layer. The results show that the longer the adhension length, the higher the strain transfer rate. When the adhesion length reaches a certain level, the strain transfer rate in the middle of the optical fiber is 1, and those of the both ends are gradually reduced. The higher the shear modulus of the coating layer and the adhesive, the greater the strain transfer rate. Therefore, coating fibers and adhesives with high shear modulus should be used in engineering applications, and the adhesion length should be greater than the length of the area to be measured.