Abstract: The Dahongshan Iron-Copper Deposit in Central Yunnan is the largest exploited iron-copper deposit in Yunnan Province. Its deep mining has formed numerous concealed goafs, which may induce ground pressure hazards that threaten mine safety. Accurately determining the spatial location and morphology of these underground goafs is a critical technical challenge for establishing a green mine disaster prevention system. Transient electromagnetic method (TEM) is currently the most widely used electromagnetic geophysical method for detecting goafs. However, despite its extensive application, TEM suffers from a shallow detection blind zone and is susceptible to interference from the complex electromagnetic environment in underground settings. To overcome this bottleneck, this study introduces the Opposing-Coils Transient Electromagnetic Method (OCTEM). By utilizing reverse currents in dual coils to generate a zero-flux plane, this method effectively eliminates primary field interference, enabling high-precision measurement of the pure secondary field underground. OCTEM boasts strong anti-interference capability, high resolution, and suitability for operation in confined spaces. Focusing on the goafs between exploration lines A33 and A34W in the west mining area of the Dahongshan deposit, the study first verified the effectiveness of the method in the known E2 goafs, followed by refined detection. By deploying multi-angle survey lines at the 360 m and 365 m levels and performing data inversion, the high-resistivity gas-filled goafs and the interfaces of medium-resistivity loose bodies were successfully identified. The results indicate that OCTEM can precisely delineate the electrical structure of the goafs, comprising the "roof-empty zone-loose body-floor," effectively overcoming the shallow blind zone limitations of traditional methods. This provides a scientific basis for the safe and efficient recovery of deep resources and ground pressure regulation in the mine.