Copy-paste processing is a frequently used method to tamper an image. For JPEG format is the mostly employed image format, more likely the copied slice came from JPEG image. In this paper, we first introduce two copy-paste tampering Scenarios: one is conducted between JPEG images and saved in a loss less format, the other is also conducted between JPEG images, but is saved in the JPEG format. Then we analyze and simulate the detection method for the two tampering Scenarios. We detect the tampered region by computing the sum of absolute difference images between the tampered image and a resaved JPEG compressed image at different quality factors. Experimental results show that our method can effectively detect the tampered region in two tampering Scenarios.