High-frequency pressure monitoring (HFPM) is a real-time, easy to operate and cost-effective method for hydraulic fracturing diagnostics. It enables the rapid assessment of injection point depth, fracture initiation position, temporary plugging and diversion effects and mechanical plug sealing. By analyzing water hammer pressure waves stimulated during the fracturing process, it facilitates the evaluation of fracturing stimulation effectiveness, guiding on-site construction decisions, resource allocation rationalization, and the comprehensive development of shale gas reservoirs. In this study, HFPM is employed to evaluate the temporary plugging effect and mechanical plug sealing efficiency in the fracturing of a horizontal shale gas well in Changning. Additionally, the complexity of the fractures is assessed based on the attenuation characteristics of the water hammer pressure wave. A comparative analysis is conducted between the diagnostic effects of HFPM and the pressure increase method before and after temporary plugging. HFPM demonstrates a higher ability to identify temporary plugging turning effects, with a recognition rate increasing from 45% to 75%, and exhibits superior diagnostic performance. The application of HFPM can contribute to the optimization of fracturing process parameters for shale gas horizontal wells and facilitate the efficient development of shale gas reservoirs in China.