Geological archives document the spatiotemporal development of the Neo-Tethys Sea and surrounding orographic uplift over the early Cenozoic, yet their impacts on the Central Asian climate and vegetation evolution during the Paleocene remain poorly understood because the regional quantitative studies are rather limited. Here, we employed Leaf Margin Analysis (LMA), Leaf Area Analysis (LAA), and Climate Leaf Analysis Multivariate Program (CLAMP) to quantitatively reconstruct the early Paleocene climate of the Altay flora in Xinjiang, northwestern China. The climatic estimates were derived with a mean annual temperature (MAT) of 14.1 degrees C, a warmest month mean temperature (WMMT) of 23.1 degrees C, a coldest month mean temperature (CMMT) of 5.7 degrees C, a length of growing season (LGS) of 8.4 months, a growing season precipitation (GSP) of 158.6 cm, a three wettest months precipitation (3-WET) of 80.7 cm, and a three driest months precipitation (3-DRY) of 24.6 cm. Moreover, the minimum temperature of coldest month and continentality index were calculated as 2.3 degrees C and 17.4, respectively. These results signify that a warm temperate marine climate dominated Paleocene Altay and showed weak seasonality in temperature and precipitation, especially lacking scorching heat in summer and extreme cold in winter. These early Paleocene ecological conditions are also evidenced by the coeval neighboring floras representing warm temperate coniferous-broadleaved forests, but differ significantly from the modern analogues in Central Asia. The major climatic and vegetation differences between Paleocene and present-day were probably driven synergistically by (proto-)Paratethys Sea retreat, orogenic uplift and global cooling after the Paleocene.