The evolution of deserts is sensitive to climate changes. However, the trends and evolutionary processes of deserts under global warming remain controversial. The late Pliocene serves as a climatic analog for future conditions. Therefore, reconstructions of desert distributions during this period can provide a valuable historical reference frame for predicting the evolution of deserts under future warming scenarios. Aeolian depositional sequences on the Chinese Loess Plateau (CLP), located at the down-wind direction of the desert, serve as a direct record of desert expansion and contraction. Previous reconstructions relied on the relationship of the grain-size patterns on the Chinese Loess Plateau and the desert margin position during the Last Glacial Maximum. In contrast, we propose a new model based on Holocene desert margin and loess grain-size distribution, and apply it to reconstruct desert margins during the Pliocene warm period. Our new results show that, during the late Pliocene, the southern margin of the proto-Mu Us sand fields was approximately 260 km north of the modern boundary. This study suggests that, in the absence of human disturbance, deserts in northern China may contract under future global warming.