Copy-paste is a kind of local tampering technology of image. It copies a certain area in the image, pastes it to the disjoint area of the same image, and carries on certain post-processing operation. In order to remove an important feature in the image. There are usually two identical (or similar) regions in the image after copy-paste tampering, and in general, the copy-paste tampering of the image content is usually connected and large area, and there is a correlation between the image copy area and the paste area, that is, the corresponding similar image block pair has the same offset vector. it can be seen that the copy and paste regions should be connected region pairs composed of many adjacent image block pairs with the same offset vector, rather than a set of scattered similar block pairs. Therefore, if there is a copy-paste region in the image, the statistical value of the corresponding offset vector should be large and much larger than that of the other offset vectors. To sum up, this paper presents a basic image copy-paste tamper model,