The Qaidam basin hosts a great quantity of salt- lake resources. The shallow, easily exploited, high- quality resources have decreased continuously with progressive exploitation risking sustainable development. It is therefore essential to locate and exploit deep resources. In comparison to the shallow part, the deep part of salt lakes mainly contains brine- type resources. It is difficult to exploit deep resources due to relatively low reservoir quality and unstable hydrological conditions. This study focuses on the extensional fault zone in the Bieletan area and the Qaidam salt lakes and aims to clarify the distribution pattern of fault zones, the variations of reservoir thicknesses and aquosity based on the remoting sensing interpretation, gravity measurement, source acoustic magnetotelluric survey. The results show that there are two brine- enriched fault zones in the Upper Pleistocene reservoir, located in the deep part of our study area. The “brine converging gallery” in fault zones is accurately located by radon anomalies, and validated by drilling and pilot production. This study not only supplies important basis for prospecting and exploiting deep brine resources in the Bielatan area, but also details and improves the theory of deep brine ore- controlling fault zones in the salt lakes.