1. A real-time birefringent imaging spectrometer based on differential structure, which comprises: a object lens ( 1 ) provided to image the object; a field stop ( 2 ) provided to limit the field of view; a collimator lens ( 3 ) provided to collimate the objective light; a lenslet array ( 4 ) provided to incorporate image replication; a first polarizing beam splitter ( 51 ) provided to split the objective light into two orthogonally polarized components; an imaging branch to receive the light reflected by said the first polarizing beam splitter ( 51 ); a spectral branch to receive the light transmitted by said the first polarizing beam splitter ( 51 ) via the lenslet array ( 4 ); a second polarizing beam splitter ( 71 ) provided to split the light transmitted by said spectral branch into two orthogonally polarized components; a transmitted spectral branch to receive one of output lights from said second polarizing beam splitter ( 71 ); a reflected spectral branch to receive another of output lights from said second polarizing beam splitter ( 71 ).