As one of the main pasting way of fiber optical grating (FBG), the surface bonding has the feature of easytouse and widely used. The raster grid area of FBG is about 1.0 cm to 1.5 cm centimeter. The result reflected by the interrogator is the overall change of the raster grid area and the actual bonding length will affect measuring result. The influences of different bonding lengths of FBG on the are experimentally studied in this paper. It has been found that the longer of bonding length, the less error of the measuring result and the actual strain. The result will provide a reference for FBG packaging.