Fiber Bragg grating under local transverse force was studied theoretically and experimentally. Based on the transfer matrix method, the consequential changes in reflected spectrum under local transverse force are analyzed, the corresponding mathematical model is established, and the mathematical expressions are deduced. When fiber Bragg grating is pressed by local transverse force, the reflection spectra are independent of the applied length. The wavelength of split point is periodical and linearly proportinal to the applied force. And the reflectivity of split point is approximately hyperbolically tangential versus the applied position.