Abstract: In order to promote the development of firefighters' physical fitness, an index system of influencing factors of firefighters' physical fitness development is constructed from five dimensions: self, training, management, security, and fire protection characteristics. The degree of influence, affected degree, centrality, and cause of 22 influencing factors are calculated by using the decision test and evaluation laboratory method (DEMATEL), and the multi-level hierarchical structure model of influencing factors of firefighters' physical fitness development is constructed by combining the interpretative structural model method (ISM), so as to realize a comprehensive understanding of the importance, causal attribute, logic and hierarchical structure of the factors in the system. The research shows that the 22 influencing factors include 12 cause indicators and 10 outcome indicators, of which 13 indicators such as health status and training recovery support are the key factors affecting the physical development of firefighters. In the multi-layer hierarchical structure model, the physical training load is the most critical indicator at the surface factor level, the physical recovery status is the most critical indicator at the middle factor level, and the health status is the most critical indicator at the secondary factor level, the comprehensive environment of physical training is the most critical indicator at the level of essential factors.

Key words: Key words: fireman, physical fitness, physical training, DEMATEL, ISM