Abstract: This paper proposes an incomplete S-shape model theory, in view of the limitation that the existing S-shaped model is more suitable for the prediction of developed countries.The specific calculation method of the relative parameters of the incomplete S-shaped model equation is given through mathematical analysis, and based on the nineteenth People’s Congress’s grasp of the direction of China’s future medium and long term economic and social development, the consumption trend of automobiles which is the downstream of lead is analyzed.Finally, this paper forecasts the demand of refined lead in China in 2020-2050.The forecast results show that lead demand will reach its peak value before and after 2028, with a peak demand of about 5.835-6.172 Mt and the per capita demand for lead is about 4.16-4.17 kg.The prediction results will provide references for the development and utilization of lead resources and policy-making of related industries in China in the medium and long term.