This paper investigates the application of intelligent diagnostic systems in the predictive maintenance of gas pressure regulating devices. It analyzes the limitations of traditional maintenance models in terms of cost, efficiency, and safety, and explores the advantages of intelligent diagnostic technologies for pressure regulators in fault diagnosis and condition assessment. Through a real-world case study in Jinshan District, Shanghai, the effectiveness of this technology in non-disassembly testing, high-precision pressure monitoring, and intelligent diagnostics is validated, enabling precise evaluation and fault prediction of critical components such as pressure regulators, shut-off valves, and relief valves. The research demonstrates that this diagnostic system can significantly reduce maintenance costs, enhance gas supply safety, and improve equipment reliability, thereby providing a viable pathway for the transition of gas pressure regulating devices from scheduled to predictive maintenance.