In the uncooled optical readout infrared imaging technology based on knife edge filter, the reflection of the optical elements bring in stray light spots in the CCD target surface. It makes the proportion of FPA image in the detected light intensity signal reduced, thus the sensitivity of optical detection is reduced. A polarized optical readout system was proposed. Polarizers and a quarter wave plate are added to the system. The polarizing beam splitter is used to replace the original beam splitter. The reflected stray light of the optical components in the optical path is thus eliminated. The proportion of the FPA image received in the CCD target surface substantially increased, so the optical detection sensitivity is enhanced. The polarized optical readout infrared imaging experiment result showed that the detection sensitivity increased by about 47% than the non-polarized system, which is close to the theoretical value.