Delayed geochemical hazard(DGH) of soil elements in soil will do serious harm to the environment.Base on the mathematical model of DGH,DGH characteristics of Cu element in the soils of Daxing Town and Yicheng.Town of Hefei were studied and compared.Results show that Cu element in the soil of Daxing Towntends to shift from release of TRCP_Cu(total releasable content of Cu element) to that of Cu_E+C(effective content of Cu element),and its DGH model was y=0.005 6x³-0.436.1x²+ 11.28x-90.803.In the soil of about 38% of the land area of Daxing Town,DGH of Cu element is very likely to break out,because Daxing Town is an important industrial town of Hefei.But the Cu element in the soil of Yicheng Town is not likely to break in to DGH,because the town is dominated with agriculture and livestock breeding.The study of DGH is of great significance to early warning of soil heavy metal pollution.