The invention discloses an infrared photoelectric detector and a preparation method thereof. The detector comprises a substrate. An optical micro-cavity lower reflecting mirror, a lower optical path difference compensation layer, an upper optical path difference compensation layer and an optical micro-cavity upper reflecting mirror which are arranged on the substrate in turn. A semiconductor carbon nano-material photoelectric device used as a light absorption material and a conductive channel is arranged in an optical micro-cavity. The position of the optical micro-cavity with the maximum cavity state density is overlapped with a working area of the semiconductor carbon nano-material photoelectric device. As for infrared light with the same wavelength, an optical path through the lower optical path difference compensation layer is the same with the optical path through the upper optical path difference compensation layer, or difference of the two optical paths is integral times of half wavelength. Capability of detecting weak infrared light is enhanced, and the micro-cavity is simple and rapid in processing technology. The detector can be applied to interconnection of carbon tube circuit photoelectric devices or interconnection of carbon tubes and silicon integrated circuit sheets so that detection and response of communication wave band infrared light are executed.