This work unveils China’s first large-scale assessment of snow leopard populations, focusing on the Sanjiangyuan region, spanning over 360,000 km2. By integrating and standardizing seven years of camera trap data (2015–2021) from 12 sites across four organizations, we obtained a population estimation of 1,002 snow leopards (755–1,341) in Sanjiangyuan, with a density of 0.90 individuals per 100 km². These findings not only highlight Sanjiangyuan’s role as a global conservation priority but also demonstrate a scalable framework for synthesizing existing data to estimate elusive species population.