In order to study the influence of targets with various polarization properties on resolution of active polarization imaging system, an experimental polarization imaging system with LED source is designed. The optical elements with high polarization extinction ratio are placed before the LED source and imaging devices. Two targets with different surface polarization properties are applied in the system. The image of imaging system for underwater environment is obtained. The experimental images are processed with inclined edge method and the modulation transfer function (MTF) is extracted. Comparing MTF results in various experimental environments using orthogonal imaging and polarization difference imaging, the conclusion is obtained that polarization technique is beneficial to suppress the forward scattered light and enhance resolution of the system. For different targets, the proper processes are applied to obtain high resolution images. Meanwhile, the conclusion is appropriate for both of linear and circular polarization illuminations.