Abstract: As an internationally advanced fourth-generation light source with ultra-high brightness and ultra-low emittance, the High Energy Photon Source (HEPS) imposes stringent requirements on the sealing performance and cleanliness of its vacuum system. Vacuum leak detection and residual gas analysis are key procedures to ensure the vacuum system meets performance standards. This paper systematically elaborates on the strategies and practices of vacuum leak detection for the HEPS storage ring vacuum system during the installation, commissioning, and operation phases. It focuses on expounding the leak detection scheme using the vacuum mode method of helium mass spectrometer leak detectors, detailing the procedures and solutions for locating various leak points (such as weld defects and improper installation of sealing rings), and analyzing the typical response characteristics of the instrument interface during leak detection. Meanwhile, this paper deeply explores the dual roles of Quadrupole Mass Spectrometers (QMS) in the commissioning of vacuum systems: on the one hand, as a high-sensitivity leak detection tool, it assists in locating difficult-to-detect leaks that are challenging for helium mass spectrometer leak detectors; on the other hand, as a key device for residual gas composition analysis, it systematically measures and compares the residual gas spectra in the vacuum chamber of the storage ring before and after beam loading. This study verifies the effectiveness and reliability of the adopted leak detection methods and analysis strategies, providing a solid guarantee for the qualification and stable operation of the HEPS storage ring vacuum system. Its experience holds important reference value for vacuum quality control and analysis of similar large scientific facilities.