Sampling was conducted according to field survey and measurement and, on such a basis, the authors studied the component features of the city wall's earth in the Neolithic Liangzhu City, and further discussed its source in association with the analysis based on experiments of XRD, grain size and geochemical elements. The results are as follows: ① Characteristics of grain sizes, geochemical elements and clay minerals are similar to those of Mantou and Huangnikou mounds, and the northern city wall's earth is dominated by clay silt. Clay minerals comprising city wall's earth belong to the combination of illite-kaolinite-vermiculite/mixture of chlorite and vermiculite-smectite. Padded earth's characteristics in northern city wall are similar to earth's characteristics of the fourth layer widely distributed in this area. It is therefore inferred that the source of the city wall's earth was derived from somewhere near Mantou and Huangnikou mounds. ② Mounds like Mantou went through strong oxidant activity because of its high elevation. The raw earth consisting of lacustrine-swamp facies went through reduction activity because of its low elevation, resulting in differences in mineral component degree of crystallinity and geochemical elements. The Neolithic people in Liangzhu area used the local earth only for the city wall's foundation, and they didn't use it to build the city wall directly. They chose the soil from somewhere near mounds like Mantou, because they thought the soil there was more suitable to building city wall.