The sources and accumulation of heavy metals in soil are of great significance for soil utilization and pollution control. Lead (Pb), a common heavy metal element, tends to accumulate in the soils with time. Excess Pb in soils accumulates in plants and becomes toxic to humans and livestock when it enters the food chain. The historical data of Pb contents in soils in northwest China were studied to establish the historical change curve in this paper. The results indicate geochemical background and wind and dust deposition have the minor contribution to the accumulation of Pb in soils, but human activities have caused a rapid accumulation of Pb in soils. From 1990 to 2020, the accumulation of about 0.1 mg/kg of Pb in the soils is due to natural wind-dust deposits, but the content of Pb in the soils has nearly tripled from about 22 mg/kg to about 52 mg/kg with the process of anthropogenic urbanization and industrialization. We found that the influence of human activities on lead content was closely related to the total primary energy production (10,000 tons of SCE), and the evolution of soil Pb contents in the study area was consistent with the Allometric1 model.