Abstract: “Engineering is the driving force behind mechanics” is a research philosophy consistently advocated by Prof. Qian Lingxi, inspiring succeeding generations to work diligently at the forefront of engineering mechanics. Guided by Prof. Qian’s ideas, Lin Jiahao established the pseudo excitation method (PEM) for efficient analysis of random vibrations in the 1990s, which remains remarkably effective in solving engineering problems to this day. Subsequently, Zhang Yahui, following the research philosophies of Prof. Qian and Lin, pioneered the fatigue response spectrum method (FRSM) in response to the growing demand for vibration fatigue assessment, providing a convenient and effective approach for predicting vibration fatigue in complex engineering structures. This paper focuses on the core theories of the PEM and the FRSM, as well as their engineering applications to vibration fatigue problems. Taking an aircraft engine inlet structure as a typical case, it demonstrates the outstanding effectiveness of these two methods in the vibration fatigue assessment of engineering structures, further showcasing the ongoing continuation and development of Prof. Qian’s philosophy.