The interaction between railroad engineering and land resource occupation in mountainous ar-eas was analyzed,elements of railroad engineering and land resource occupation extracted and an index system of the elements constructed.A model was built for identifying the key elements of land saving in railroad engineering in mountainous areas,a two-layer complex network established,the importance of elements'own attributes calculated by using the entropy power method,node connection strength and inter-layer connection coefficient determined by using fuzzy set theory,and the comprehensive impor-tance of elements determined by the complex network model.Combined with an actual case analysis,the key land-saving elements of this section were found to be line alignment,utilization of existing roads,uti-lization of existing corridors,tunnel slag,tunnel ratio,bridge ratio,reasonable planning of construction right-of-way,etc.