As an important part of the latest climate change scenarios in IPCC, the Shared Socioeconomic Pathways (SSPs) play an important role in assessing climate change impacts and supporting climate policy decisions. In this study, we propose a technical solution for localization, parameterization and spatialization of SSPs at county level using PDE model and C-D model. We carry out population and economic projections of 101 counties in Inner Mongolia, China during 2010–2050 under five SSPs as a demonstration. It is founded that population and GDP varies from different counties significantly, and shows the patterns of high in east and low in west, high in south and low in north. The spatial distribution of GDP is positively related with the population. The total population increases first and then decreases from 2015 to 2050 in Inner Mongolia. By the ends of 2050, the population reaches 23.32 million (−9.46%), 24.14 million (−2.30%), 24.72 million (+0.05%), 22.37 million (−9.46%), 23.49 million (−4.93%) under SSP1, SSP2, SSP3, SSP4, SSP5 scenarios. The largest gap of population is 2.35 million between SSP1 and SSP4. The GDP grows constantly from 2010 to 2050 in Inner Mongolia, but the growth rate is slowing down. By the ends of 2050, GDP reaches 5.09 trillion (+4.75 times), 5.22 trillion (+4.90 times), 4.41 trillion (+3.98 times), 4.98 trillion (+4.62 times), 5.87 trillion (+5.63 times). Therein, the biggest gap of GDP is 1.5 trillion between SSP4 and SSP5. The results provide technical support for population and economic scenarios under SSPs at a small regional level, and provides scientific basis for the formulation of climate change policies in order to formulate measures to deal with climate change risks.