A CFAR target detection method is proposed for nonhomogeneous environment in UWBSAR image with variability index and order-statistics CFAR detection.The method can select appropriate cells in non-homogenous regions for clutter environment power estimation.The designed detector can keep CFAR performance in multi-targets environment and irregular boundary of non-homogenous regions.Experimental results show that the novel method can offer better detection performance than traditional cell average CFAR detection methods.