Optical and thermal properties of a novel optically readable thermal imaging focal plane array (FPA) are analyzed, including reflectivity of two reflective surfaces of Fabry-Perot micro-cavity, temperature response of movable micromirror, noise-equivalent temperature difference (NETD) and thermal response time. Theoretical analysis indicates that when the two reflective surfaces of Fabry-Perot micro-cavity have same reflectivity of 0.5 better reflective light intensity and modulation degree can be achieved and that reflective light intensity varies linearly with the displacement of micro-mirror in the range of 0～λ/4. Temperature response of the movable micromirror, NETD and thermal response time are estimated as 2.05×10-4, 19.5 mK and 1.54×10-3 s, respectively.