This paper discusses the design of an uncooled optomechanical infrared imaging system. A micromachined micro-cantilever array serves as an uncooled infrared imaging sensor known as focal-plane array (FPA). When exposed to an infrared source, the absorption of the incoming radiation energy by the cantilever will raise its temperature. Due to the thermal expansion mismatch of the two materials, the temperature rise will induce bending of the cantilever. The pixel design based on considerations of thermal, mechanical, and optical properties, and also compatibility with micro-fabrication process has been described in detail. By detecting the deformation of the cantilever optically using a laser interfometry system, the thermal information of the infrared source can be extracted. The paper describes the microfabrication process of the FPA, and a primary test on the temperature response of the pixel shows reasonable agreement with the theoretical analysis.