Abstract: To solve the problem of poor resolution in passive millimeter wave (PMMW) imaging, we present an improved maximum a posteriori (MAP) super-resolution algorithm. The algorithm combines the advantages of Wiener filter restoration algorithm and MAP algorithm based on Poisson distribution. The Wiener filter is employed to restore the pass-band spectrum, and the MAP algorithm is applied to complete spectral extrapolation as the main iterative process to ensure that low-frequency component is not destroyed as spectral extrapolating. Meanwhile, the computational complexity and real time of the algorithm are analyzed. Furthermore, simulation results show that the algorithm can effectively restore the frequency out side the cut off frequency, enhances the resolution and can be implemented by parallel processing.