When fiber Bragg grating (FBG) strain sensor is applied to practical enginee ring applications,it is usually embedded in or adhered on the surface of the matrix.Due to the differences of ph ysical-mechanical properties of optical fiber,protective layer,paste layer and matrix material,the strains me asured are unequal to the actual strains of the matrix by an FBG strain sensor.So the improved measurin g method is needed in practical engineering applications,and the strain result which is measured by an FBG strai n sensor is needed to be corrected in response to the real strain.As a study of substrate FBG strain sens or in this paper,a simple strain transfer model is established,and the strain transfer model is shown as “matrix structure－colloid－substrate－colloid－FBG sensor”.the strain transfer formula between the strain measured by substrate fiber Bragg grating strain sensor and the actual strain of the matrix is derived by the stra in transfer model,and the theoretical results have been confirmed by finite element analysis and experimental verifica tion.The theoretical derivation is verified by the finite element analysis and experiment.The strain transfer form ula derived in this paper can be applied to practical engineering.