Abstract: In this paper, a new algorithm based on polarimetric distance transformation is proposed for the change of specific land cover type in complex scenes. Firstly, an improved Wishart distance algorithm was used to measure the distance between the target land cover type and two phase fully polarimetric images，Then, the ratio logarithm of the measurement was transformed to construct difference image. Finally，double threshold segmentation method was applied to extract the change areas and to distinguish two kinds of changes. Two Radarsat2 fully polarimetric images in Suzhou city, China, acquired on April 9, 2009 and June 15, 2010, were used for experiment. The results show that the proposed algorithm gives a good performance to achieve the change of the specific land cover type in complex scenes and has good robustness.