Abstract: To provide the mensurable evidence for early-warning of soil heavy metal pollution, base on the mathematical model of delayed geochemical hazard (DGH) and according to experimental data of Zn element in soil, the DGH characteristics of Zn element in soil of Daxing town and Yicheng town in Hefei area were studied and contrasted, then the model of Zn element was determined. The results show that in Daxing town the Zn element in soil has the inverting trend form total releasable state to exchangeable and carbonate state, the critical concentration of Zn element in soil was 70.333mg/kg, DGH of Zn element has the possibility to break out in about 22.6% soil area. In Yicheng town, DGH has no possibility to break out.