1. Heilongjiang Mining Group Co. Ltd，Harbin 150036，China; 2. Geophysical Exploration Institute of Heilongjiang Province，Harbin 150036，China; 3. Heilongjiang Province Geology and Mineral Ｒesources Test and Application Institute，Harbin 150036，China

Cuihongshan Fe polymetallic deposit is a deposit in skran type． The deposit is characterized by strong magnetism and low resistivity， which provides precondition to deep prospecting in the mining area by CSAMT method． The authors use magnetic and CSAMT methods to detect the general survey in the field work． According to two-dimension inversion of highly precisive magnetic surveying data processing and measured data by CSAMT meth- od， the authors delineate high magnetic anomaly and explain low resistivity anomaly and background area， and infer the position，depth and scope of ores． The scale of Cuihongshan Fe polymetallic deposit rise up to large scale de- posit by the discovery of thick ore body，and the effectiveness of CSAMT method in deep prospecting has been veri- fied．