A design of optical readout uncooled thermal imaging pixel is proposed. The theoretical analysis shows that,thermal-mechanical sensitivity reaches 0.043 deg·K-1 and increases by 79% at least when the pixel size decreased by 75% compared with reported ones. Sensitivity can be adjusted from 2.36×10-6 rad·m2·W-1 to 9.21×10-6 rad·m2·W-1 by changing the size of the bottom gold layer on the folded cantilever. Finite element simulations by ANSYS are in good agreement with theoretical results,which verifies the validity of the design.