The imaging resolution of a polarization detection system in the focal plane is lower than the actual resolution of the detector owing to the influence of the detector structure. In this study， micro-scanning is used to obtain the micro-displacement frame sequence without changing the optical system structure， and an improved convex set projection （POCS） algorithm is proposed to improve the imaging resolution of the polarization imaging system. In the algorithm， the obtained polarization microscan image sequences were first separated through angle detection， and the same group of angle detection image sequences were used as the input. Second， displacement matching and convex set projection iteration were conducted to initially reconstruct high-resolution images. Thereafter， the images were grouped into sliding window non-neighborhood clustering， and the dimensionality of the clustered images was reduced through principal component analysis. Finally， each one-dimensional information was regarded as a time sampling function， and soft threshold denoising was conducted in the wavelet domain. Experiments demonstrate that this algorithm can effectively improve the anti-noise performance of the conventional POCS algorithm， improve the imaging resolution of the high-resolution focal plane polarization detection system， increase the structural similarity coefficient by 0.02， increase the peak signal-to-noise ratio by 1 dB compared with similar algorithms， and achieve higher noise robustness.