Abstract. The collapsibility has become a key material property to study strength and deformation behavior of loess, which is closely related with its micro structural character. In this paper, the authors firstly obtained simple micro-structural parameters both on loess samples of before and after collapsing from the Electron Scanning Microscope images, then made a comparative analysis of relationship among these simple parameters and constructed synthetic micro-structural parameters. Finally the authors presented equations for prediction the relationship between collapsibility coefficient and synthetic micro-structural parameters. It is shown that the collapsibility of loess can be evaluated objectively using the proposed method. The study provides efficient exploration in quantificational studying the effects of microstructure on collapsibility of loess.