Investigating the ecological security changes in Qinghai Province, quantitatively evaluating its ecological security, and diagnosing obstacles affecting ecological security can provide a theoretical basis for ecological protection and high-quality development in Qinghai Province and even the Qinghai-Tibet Plateau region. This study focuses on Qinghai Province, constructing an ecological security evaluation index system based on the DPSIR model. It utilizes the entropy weight TOPSIS method to analyze the spatiotemporal evolution characteristics of ecological security from 2010 to 2020 and applies the obstacle degree model to diagnose the main factors affecting ecological security. The research findings indicate that during the study period, the ecological security index of Qinghai Province increased from 0.31 in 2000 to 0.71 in 2020, with the ecological security level transitioning from relatively unsafe to relatively safe. Overall, the ecological security situation is steadily improving. At the prefecture level, Hainan Prefecture experienced the largest increase in ecological security index, while Yushu Prefecture had the smallest increase, reflecting a spatial evolutionary pattern from “leading in the east” to “surpassing in the southeast”. Through obstacle factor diagnosis, it was found that the main factors affecting ecological security in Qinghai Province shifted from insufficient intellectual capital and pollution emissions to the development of animal husbandry and population growth. Recommendations to enhance ecological security in Qinghai Province include strengthening the implementation of grazing prohibition, rotational grazing, and rest grazing systems, attracting high-level talents, optimizing land use, intensifying environmental protection publicity and education, and enhancing public awareness of environmental protection.