A micro-cantilever uncooled infrared(IR) detector was designed and fabricated based on standard silicon process.Because silicon nitride(S_iN_x) and aluminum(Al) have different thermal expansion coefficients,bi-material micro-cantilever that is composed of the films of S_iN_x and Al will bend when it absorbs IR radiation and its temperature changes.The variable micro-capacitor between the micro-cantilever and the substrate will change as the micro-cantilever bends.Hence,the information of IR radiation can be known when the change of the variable micro-capacitor is detected.The test of a single detector by outer apparatus shows that the micro-cantilever has strong response to IR radiation.