Abstract: Eolian theory has taken a predominant place on causes of Chengdu clay. This paper analyzed occurrence characteristics, grain size composition and quartz granule microstructure morphology of typical Chengdu clay taken from the platform of the city's east suburb. A contrastive result has demonstrated that the geographical distribution of Chengdu clay and eolian landform was inconsistent. Grain-size analysis showed that taking up two thirds of the clay component and being less than 0.01mm, the particle of Chengdu clay couldn't have been carried by wind; instead, it might be transported by running water. The leaching degree and distribution of calcium nodule showed that the clay was developed in moist environment rather than dry and hot climate. Chemical elements analysis suggests that the element content of both Chengdu clay and loess are related to their regional deposit distributions, and they are originated from different material sources.