In order to verify the correctness of the epitaxial material preparation process test, reduce the absorption of infrared light by the GaSb substrate, and at the same time improve the reliability and long-term stability of the detector, the GaSb substrate of the type-II superlattice infrared detector needs to be thinned. The backside of the GaSb substrate of the type-II superlattice detector is thinned by mechanical polishing and chemical mechanical polishing. Finally, the GaSb substrate is completely removed by etching with a special etching liquid, and the type-II superlattice material is completely exposed. Scanning electron microscope experiment shows that the barrier layer of the superlattice material can play a good blocking role, the surface of the material is smooth, and the substrate has no residue. The detector performance test results show that the performance of the thinned detector chip does not change.