A multi-aperture compound eye infrared optical system is designed for the imaging of cooled medium wave infrared detector. The optical system includes an infrared lenslet array arranged on the front spherical surface, and a relay infrared optical system matched with a cooled infrared detector. The problem of matching and connection between the infrared lenslet array arranged on a spherical surface and the relay infrared optical system matching with a cooled infrared detector is solved, and a set of multi aperture infrared bionic compound eye optical system that can match the cooled infrared detector is designed. Through the relay optical system, the focal surface imaged by the curved infrared lenslet array of compound eye is re-imaged on the focal plane of the cooled infrared detector. The waveband of the designed compound eye infrared optical system is 3.7-4.8μm. The total focal length is 3.5mm, the total field of view of the multi aperture compound eye optical system is 108°, the distortion of the full field of view is less than 6%. The design result shows that the image quality of the system with different aperture approaches the diffraction limit, and has the advantages of multi-aperture, large field-of-view, low distortion and ideal image quality.