The problem of noise reducing and resolution enhancement of SAR image was discussed.A unified regularization variation model of partial differential equation(PDE) was established,which has the noise reducing merit of PDE model and the resolution enhancement merit of regularization model.On the background of the image,the PDE model was used to reduce the noise of background,and at the targets region of the image,a background equation was used to sharp the targets firstly,then the regularization model was used to enhance the resolution of the targets.Hence,the new model can get better result on the whole image.The diffusivity based on the background of SAR was also constructed,and a forward and backward diffusion equation based on the amplitude of SAR image was obtained,which could reduce the noise of background and sharp the edges of targets.Experimental results show that the new model can enhance the strong scatter points and suppress the speckle of the image effectively.