The axial distribution of filtering response of fiber Bragg grating(FBG) along grating space is investigated,to clarify the local filtering features of FBG.Firstly,as for uniform,apodized and chirped FBGs,their axial distributions of optical field within the refection band are obtained.In uniform FBGs,the optical field is mostly reflected inside the first half length,and the local optical reflection along the whole length is asymmetric.The local optical reflection in apodized FBGs shows a uniform and symmetric distribution.In chirped FBGs,the optical field at different wavelengths is mostly reflected at different positions of grating length,following the chirp effect.The influence of refractive index and grating length on the axial distribution of reflected optical field is then analyzed.The increase of refractive index modulation leads to that the optical reflected field becomes more concentrated to the first half length,while the rise of grating length shows little impact on the local reflection area.In addition,the axial distributions of sampled FBG and sampled FBG with equivalent phase shift are analyzed as well,resulting in the exact influence of sampling function and equivalent phase shift on the axial distribution.