In this paper, the DEI images for different tissues of rat are compared. Firstly, the contrast of peak images is similar to that of apparent absorption images for the same tissues. Furthermore, the contrast of refraction image is superior to that of peak images and apparent absorption images. The DEI effect of soft tissues is more significant than that of hard tissues. The ability of refraction image is much better in distinguishing the microstructures of soft tissues. For hard tissues, there is high absorption to X-ray and their absorption contrast is relatively remarkable. The absorption contrast of high density tissues is similar to that of hard tissues. For different tissues, their refraction contrast is basically coincident, but the refraction contrast of hard tissues is slightly low. However, the imaging of brain tissue is very distinctive, both absorption contrast and refraction contrast of images is relatively high.