Abstract: To solve the problem of image quality assessment, a novel no-reference image quality assessment method is proposed based on natural scene statistics and spatial transformation. Firstly, statistical distribution of image by spatial transformation and grads are got. Secondly, asymmetric generalized Gaussian distribution model is used to simulate the distribution. And by reflection on unsymmetrical character, parameters are calculated to show distribution feature. Finally, diversity between distortion image and original image is compared and assessment value by K-L divergence is computed. Experiments reveal that this method can evaluate pictures with any kind of distortion without reference. The assessment results are better than other methods in accordance with subjective DMOS. At the same time, the complexity of calculation of this method is comparatively lower, the time for simple processing each of images in Live database is less than 130 ms, which makes it great and wide value for engineering application.