Due to advantages fibre optic sensors base on bragg grating (FBG) begin wider and wider apply for measurement systems in some industry. Furthermore, possibilities of using FBG for remote structural health monitoring especially for aviation structural elements are estimated. In this paper method of measurement axial deformation of carbon fibre reinforced plastic (CFRP) specimen with embedded FBG during tension was studied. This method allow measuring elongation of specimens with the same precision as strain gage or extensometer. The method can apply for study of distribution of axial deformation in the CFRP specimen structure undergo to tension or compression. It is possible to use this method to measuring of axial deformation of structural elements based on CFRP which are capable to preliminary loading in operating range before operation.