In this paper, it is aimed at the agricultural soil after harvest in WeiNan and its surrounding countries, researching the importance of the iron element in soil, animals and plants. organic substance content low, and the iron content also generally low. It can be broadly ranked as following: Pucheng ＞ Fuping ＞ Hancheng ＞ Dali ＞ Tongguan . The distribution of iron content of agricultural soil over the Weinna area, that is to say, is the East south low and increasing from the Eastsouth (Tongguan) to the other neighboring countries. And to some extent there minimum and maximum in each county. Natural conditions and human factors contributed to the differences in soil iron content and distribution.