Abstract: Based on the basic geological characteristics and ore-forming geological characteristics，a large number of high-precision magnetic anomaly data of Qidashan mining area and its surrounding area are obtained by adopting the high-precision magnetic survey method.The magnetic survey data are processed systematically，including reduction to the pole，the analytic continuation and direction derivation so as to suppress the interference information and highlight the useful mineral-induced abnormal information of ores in different depth.Combined with the research results of geological regularity，the development and distribution of concealed structures in Qidashan mining area are identified and the spatial distribution characteristics and regularities of orebodies in this area are clarified in detail.Therefore，the research results provide theoretical basis and technical guidance for prospecting for reserves increase in deep and marginal exploration in Qidashan iron deposit，but also provide reference for exploration of deep and hidden orebodies in regional BIF-type iron ore deposits.

Key words: High-precision magnetic method, Concealed structures, Qidashan iron deposit