Separate detection of the degenerate mode groups (DMGs) of multimode fiber was realized by using a multimode tilted fiber Bragg grating (TFBG). With multimode TFBG, the DMGs were coupled into the radiation ray that was focused separately on the focal plane of a lens. The radiation ray corresponding to the nondegenerate mode group is separated on the focal plane, so that the radiation ray of DMGs was selected and detected. The experiment of DMG separate detection was conducted with a standard communication multimode fiber with a core diameter of 62.5 μm. The multimode fiber was excited by a single mode fiber, and optical power of DMGs was measured while changing the lateral misalignment of exciting fiber. The measured results of the lowerorder DMGs were in consistence with the numerical results, but there appeared a few deviations for the higherorder DMGs. Further experiments needed to be conducted to verify the idea of exciting a single DMG in a multimode fiber using a TFBG and then measuring the coupling coefficient under this condition.