Anatexis is a commonly observed phenomenon in high- grade metamorphic rocks and plays a crucial role in the tectonic evolution of the orogenic belt. Eclogite, as the primary rock type, is extensively studied for its significance in continental subduction, ultra- high pressure (UHP) metamorphism, and crust- mantle interaction. Partial melting of eclogite is closely linked to crustal growth, slab exhumation, and the transport and distribution of elements within continental subduction channels. In the North Qaidam UHP metamorphic belt, the Xitieshan eclogite preserves in- situ and in- source leucosomes, which serve as indicators of anatexis. These leucosomes provide favorable conditions for understanding the effect of the anatexis on UHP eclogite. This paper focuses on the zircon U- Pb chronology analysis of the leucosomes within the Xitieshan eclogite. Through LA- ICP- MS U- Pb dating, a weighted mean 206Pb/238U age of 425. 3±5. 9 Ma (MSWD=0. 74) was obtained, representing the formation age of leucosomes. To further understand the anatexis of eclogite in the Xiteshan terrane, thermodynamic and trace element modelling techniques were employed. Combining these models with the retrograde P- T paths of eclogite in the area, the equilibrium crystallization of Na- rich leucosomes in eclogite was constrained to temperature and pressure conditions of 794~797 ℃ and 1. 227~1. 071 GPa, respectively. The initial partial melting of the eclogite occurred during the eclogite phase (~780 ℃ and ~1.954 GPa). As the temperature increased and the pressure decreased, the partial melt formed in the UHP eclogite through the breakdown of omphacite, with minor involvement of phengite and zoisite. Throughout partial melting, eclogite generated 8~9 vol% melt, sufficient to initiate melt migration. This suggests that the eclogite likely had a limited contribution to the source area of the syn- exhumation granite in the Xitieshan terrane.