To study the strain transfer characteristics between the measured object and the distributed optical fiber sensor（DOFS）

the mechanical model based on linear elastic theory was presented.The strain transfer characteristics were analyzed by deducing the analytic solutions separately for three cases as follows:（1）the strain of the measured object distributed evenly;（2）the strain of the measured object distributed as parabolic type;（3）the interface between the measured object and protective layer slipped.The influences of the following factors such as shear strength of interface

the thickness and shear modulus of the protective layer on measurement precision were analyzed.The result shows that:strain transfer efficiency can be improved by increasing the shear strength of interface

the radius and shear modulus of the protective layer;the DOFS can reflect the strain of the measured object accurately.