Using soil magnetic susceptibility combined with geochemical,seismic and remote-sensing data,the authors made an integrated study of large-area oil-and-gas exploration in the desert region of western Inner Mongolia.The results show that the soil magnetic susceptibility anomalies are similar to hydrocarbon anomalies in distribution trend,both controlled by structure.Based on analytical results of magnetic susceptibility anomalies and magnetic mineral content in two oil-and-gas bearing local structures,it is held that the magnetic susceptibility anomalies result genetically from overall effects of secondary magnetic materials at the oil and gas bearing structural positions.Therefore,the application of this technique to the oil and gas exploration can only serve as an indirect indicator of the hydrocarbon alteration anomaly.