The uncooled IR thermal imaging technology with its wide applications in military, medical and industrial areas has been an active topic in international research. Thermal imaging based on optical readout bi-material microcantilever array is a new concept in methodology. In this paper, a new kind of bi-material micro-cantilever unit with multi-fold legs and interval gild structure is designed and its thermal and thermo-mechanical performance are analylized. A 100×100 microcantilever array is fabricated as a FPA (focal plane array), and by using this FPA, a thermal image of a room-temperature body (human body) is successfully detected. The NETD (noise-equivalent temperature difference) is about 200mK.The experimental results are well accordant with the thermal analysis of the microcantilever unit.