The invention belongs to the technical field of micro-nano photoelectric devices, and discloses a coupled cavity photonic crystal heterostructure capable of realizing wide band circular polarization,comprising a first photonic crystal and a second photonic crystal using a heterojunction interface as the boundary, wherein the first photonic crystal comprises a silicon dioxide substrate layer, themiddle of the silicon dioxide substrate layer is set as a waveguide structure along a beam incidence direction, multiple rows of germanium cylinders arranged along the beam incidence direction are embedded in both sides of the waveguide structure, and in two rows close to intermediate waveguide structure, the germanium cylinders and small germanium cylinders are arranged at intervals to form a coupled cavity structure; and the second photonic crystal comprises a germanium substrate layer, the middle of the germanium substrate layer is set as the waveguide structure along the beam incidence direction, and multiple rows of silicon oxide cylinders along the beam incidence direction are embedded in both sides of the waveguide structure. The coupled cavity photonic crystal heterostructure disclosed by the invention realizes unidirectional efficient transmission efficiency of light waves of a TE mode, a TM mode and a circular polarization mode, and can be widely applied to the field of quantum communication.