A novel zero-watermark algorithm is proposed based on non-subsampled shearlet transform(NSST) and QR decomposition for copyright protection of digital images.In this method,the host image is processed with NSST firstly,and a sub-image is extracted from the low-frequency component randomly by the Logistic chaotic system.Then the sub-image is divided into non-overlapping sub-blocks,and each sub-block is processed with QR decomposition,so the zero-watermark is derived by judging the numerical relationship between vector l1 norm from the first row elements of each sub-block’s R-matrix and the mean of vector l1 norms from the first row elements of all sub-blocks’ R-matrices.Experimental results show that the method is very robust to adding noise,filtering,JPEG compression and cropping,and can resist on the geometrical attack of rotation,scaling and translations(RST) to some extent.