University science popularization constitutes a vital force within the national science popularization system and plays a significant role in advancing high-level scientific and technological self-reliance. Addressing the persistent disjunction between knowledge dissemination and spiritual guidance—a “two separate layers” phenomenon in university science popularization—this study adopts the perspective of practice-embedded science popularization and takes the “How Steel Is Made” thematic science popularization project at the National Key Laboratory of Advanced Refractories as a case. Employing a mixed-methods approach that combines design-based research with an embedded case study, this paper constructs a three-layer mapping framework of “material process—cognitive process—spiritual imagery”. Through three rounds of iterative refinement, the project crystallized into three signature practice segments: “The Quenching of Failure, ”“The Exploration of the Micro World, ” and “The Team Crucible.” The findings reveal that the practice-embedded science popularization mechanism, pivoting on the role configuration of participants as “junior researchers, ” embeds participants into authentic scientific research processes, thereby achieving the demystification of the scientist image at the material process layer, the contextualized transformation of spiritual qualities at the cognitive process layer, and the meaning construction of value schemas at the spiritual imagery layer. Through the vertical integration of these three mechanisms, the model effectively realizes the deep coupling of knowledge popularization and spiritual internalization, offering a replicable implementation model for universities to conduct high-level science popularization and spiritual cultivation grounded in their disciplinary characteristics.