The Ko displacement theory can reconstruct the structure accurately. In order to apply this theory to the practical engineering, the optical frequency-domain reflection(OFDR) distributed fiber sensor is used as the measuring tool, and an experimental scheme of deformation estimation based on equal strength beam is designed. The experiment is divided into six stages of loading on the beam of equal strength, and the true deflection values of four measuring points under each stage load are measured by dial gauge. The deformation reconstruction of deflection is carried out according to the strain value measured at each stage. Finally, the deflection values obtained by the two methods are compared. The experimental results show that the strain coefficient of the fiber is 0.71666, the maximum error between the deflection value of deformation reconstruction and the true deflection is 0.586 mm, which is in line with the experimental expectation.