Based on the double refraction and double reflection phenomena and on the electro-optic effect of crystals, a 2×4 free-space 90° optical hybrid with an integrated structure is designed. This optical hybrid is composed of an electrically controlled birefringence crystal and a birefringence crystal which is used as an analyzer. With the electrically controlled birefringence crystal, the splitting and coupling between the signal light and the local oscillation light are realized by means of four internal double reflections and the electro-optic modulation. By adjusting the control voltage of the electrically controlled birefringence crystal and the double refraction effect of the analyzer, four-route signal-local mixed lights with a 90° phase shift are obtained. This hybrid exhibits the advantages of simple and compact structure, low loss and stable performance, which is applicable to the spatial coherence communication system.