The invention discloses an OAM photon state separator. The OAM photon state separator comprises a first N-dimensional multichannel beam splitter which comprises N incident ports and N emitting ports; a second N-dimensional multichannel beam splitter which comprises N incident ports and N emitting ports; and N SAM-maintaining Dove prism modules, wherein the k-th SAM-maintaining Dove prism module is arranged between the k-th incident port of the first N-dimensional multichannel beam splitter and the k-th incident port of the second N-dimensional multichannel beam splitter, N is a positive integer, N is greater than or equal to 2, k is equal to 1, 2,...,N, and the first N-dimensional multichannel beam splitter and the second N-dimensional multichannel beam splitter can realize N-dimensional unitary transformation.