Abstract: A new image segmentation approach using fuzzy clustering，based on rough set theory，is presented.By extracting encrustation of histogram，and calculating partial fuzzy extent around pixels to update the fuzzy roughness.Using fuzzy roughness and local operator to update the membership function of FCM algorithm.In rough-set theoretic sense，the histogram correlates with the lower approximation and encrustation of histogram correlates with upper approximation.Compared to traditional fuzzy clustering segmentation algorithm and Liu’s approach，not only reduce the time complexity，but also present obviously result of clustering. From the test，the method has stronger convergence，shorter running time，and good segmentation results.