Mercury (Hg) provides critical information on terrestrial planet formation and evolution due to its unique physicochemical properties and multiform isotopic compositions. Current knowledge of Hg is mainly limited to Earth's surface environments, and the understanding of Hg in the Earth's interior remains unclear. Accretionary orogens are major settings for continental crustal growth and crust-mantle interactions. We studied the Hg concentration and isotopic composition of igneous rocks in the eastern Central Asian orogenic belt, using Hg as a proxy to trace the recycling of surface materials in Earth's lithosphere. Our results show low Hg abundances in mafic through felsic igneous rocks (4.93 +/- 4.35 ppb, standard deviation [SD], n = 267). Mafic rocks show slightly lower delta Hg-202 (-2.9 parts per thousand +/- 0.5 parts per thousand, SD, n = 24) than intermediate (-2.4 parts per thousand +/- 0.8%, SD, n = 58) and felsic (-1.5 parts per thousand +/- 0.8 parts per thousand, SD, n = 185) rocks, indicating a chemical stratification of Hg isotopic composition in the continental crust with isotopically lighter Hg in the lower part and heavier Hg in the upper part. Slightly positive.199Hg values are observed in mantlederived mafic (0.07 parts per thousand +/- 0.06%, SD) and intermediate (0.06 parts per thousand +/- 0.07 parts per thousand, SD) rocks, which agree well with those reported for marine sediments, indicating the involvement of fluids or melts from the oceanic crust. Larger variations of Delta Hg-199 values (-0.26 parts per thousand to +0.21%, average: 0.01 parts per thousand +/- 0.08 parts per thousand, SD, n = 185) are observed in felsic rocks, further indicating recycling of surface Hg from the marine reservoir via slab subduction (reflected by positive values) plus magmatic assimilation of terrestrial Hg (reflected by negative values). Our study demonstrates that Hg isotopes can be a promising tracer for the chemical dynamics of Earth's lithosphere.