The development of the engineering workforce has been elevated to a national strategic issue in China, yet systematic research on the spirit of engineers remains underdeveloped, and its conceptual definition, theoretical framework, and strategic relevance all await deeper inquiry. Grounded in the fundamental theories of the philosophy of engineering, this study starts from the threefold determinations of engineering activities—purposiveness, cognition, and normativity—and argues that the spirit of engineers is the internalization and sublimation of engineering activities within the engineer's professional identity. On this basis, it proposes a three-dimensional analytical framework of "mission‒thinking‒character," condenses the spirit of engineers into a sixteen-Chinese-character formulation: "following principles to innovate, acting pragmatically with responsibility; coordinating to optimize, collaborating to achieve success" (xunli chuangxin, wushi dandang; tongchou qiuyou, xietong shancheng), and preliminarily tests the explanatory power of the framework by using both positive and negative engineering cases. The study further analyzes the relationships between the spirit of engineers and the spirit of scientists, entrepreneurs, and craftsmen, clarifying the distinctiveness of the spirit of engineers, and reveals that the inheritance and promotion of this spirit depend on the coordinated interconnection of three major fields: school education as the foundation, engineering practices as the tempering ground, and social culture as the nourishing environment. To translate the inheritance and promotion of the spirit of engineers from a theoretical proposition into a sustainable institutional reality, the study proposes policy recommendations including incorporating the spirit of engineers into the CPC's spiritual pedigree, improving the engineer evaluation system, deepening engineering education reforms, strengthening the engineer honor and recognition system, and fostering a social atmosphere that respects engineers. The study can provide theoretical and managerial references for the cultivation of excellent engineers and the development of the engineering professional system.