Abstract: Mulonggou iron deposit is contact metasomatic skarn type deposit, and its geological tectonic units belong to Taihua ancient land mass of the North China Craton. The main surrounding rock formation is Xunjiansi in Jixian system, invaded by bifurcation. The ores are distributed in the inner and outer contact zone of granite diorite porphyry in middle Yanshanian and Xunjiansi. The mineral composition is simple, including mainly magnetite and other metal of industrial significance, such as Fe, Mo, Zn, Pb, Cu. Based on the metallogenic characteristics of ore body and alteration studied in this paper, we conclude that the metallogenesis is mainly controlled by geological structure and intermediate-acid magmatic activity, besides, calcium-magnesium carbonate is favorable surrounding rock for mineralization.