///The Awulale Mountain copper metallogenic belt is a major copper producing area in Western Tianshan, and the Nulasai copper deposit is a typical small-size copper deposit. The authors carried out a systematic study of the geological features as well as the origin and evolution of metallogenic fluids in the Nulasai copper deposit. Characteristics of ores, mineral phases, fluid inclusions and stable isotopes show that the Nulasai copper deposit belongs to middle-low temperature hydrothermal metallogeny, rather than secondary enrichment metallogeny. The metallogenic process belongs to one period consisting of four stages. Fluid mixing of pneumatolito-hydrothermal fluids played a key role in metallogeny. The Nulasai copper deposit and the Mosizaote rock mass are closely related to each other in time and space. The original fluids of Nulasai were derived from pneumatolito-hydrothermal fluids, and Mosizaote provided heat for metallogenic process.