As an effective technology for earth remote sensing, synthetic aperture radar (SAR) provides high-resolution, wide-swath, day-and-night and weather-independent images for observation region, which has been widely used for military reconnaissance, environmental monitoring, geological mapping, et al. With the developments of radar technology and geoscience, more target characteristics are expected to be acquired. Conventonal single-polarimetric SAR has been difficult to meet diversified requirements for practical applications. Based on multi-polarization, polarimetric synthetic aperture radar (PolSAR) can obtain target characteristics under different polarization state. PolSAR enriches information of SAR images, whose applications are further expanded. Scattering mechanism interpretation is an important bridge between the collected data and real applications. In this paper, the research progress of PolSAR is firstly reviewed, with emphasis on polarimetric target decomposition. Processing results of real data is presented. Finally, some possible directions for future development are proposed.