The invention discloses a normal-temperature far infrared inner satellite imaging detector, suitable for detecting an inner satellite and belonging to the technical fields of spacecraft systems and measuring instruments. For detecting an inner satellite in a closed small-size space, the invention provides a far-infrared wave band-based infrared imaging detector system which comprises a short-focus lens, an infrared focal plane array of a non-refrigeration type, a data acquisition circuit and an image data processing unit, wherein the short-focus lens is suitable for imaging an object at a distance of 100-500 mm in a waveband of 8-12 mu m, and the infrared focal plane array of the non-refrigeration type working in the far-infrared waveband can induce a hot source at a normal temperature. Under the conditions of being independent of a light source and a temperature reference chip, the invention can realize the infrared imaging of a movable object under a satellite-borne small-size closed environment.