Abstract: In this paper, porosity and particle micro and fine structural features of Malan loess in the different regions of the Loess Plateau were analyzed. We selected undisturbed samples from Shaanxi Jingyang, Gansu Zhengning, and Gansu Heifangtai region, which we did particle analysis test. With an optical microscope and image synthesis technology, we accessed to its micro and fine structure of the image. By using the image, the pore area and the equivalent diameter are counted, as well as the quantitative parameters of the pore of the loess are obtained. The results showed that: The average particle diameter of Malan loess showed a decreasing trend from west to east, which in Gansu Heifangtai is largest, in Gansu Zhengning is center, in Jingyang is minimum. The average pore diameter of Gansu loess is rather minimal, and Heifangtai and Jingyang station are similar. The composition and structure of loess are related to the sedimentary environment, as well as, there is a relationship between the pore size distribution and composition.