Abstract: In response to the challenges in prospecting the Lehua hydrothermal fissure-filled fluorite deposit in Ningdu County, southern Jiangxi Province—namely, the unclear deep extension of the ore body and the presence of thick surface overburden—the Controlled Source Audio-frequency Magnetotelluric （CSAMT） method is employed for deep exploration. Through the interpretation of CSAMT data integrated with the geological and petrophysical characteristics of the study area, the vertical and lateral variations and extensions of lithologies and the F₁ fault, as well as the favorable locations for fluorite mineralization, are delineated along four survey profiles. Subsequent drilling validated the deep extension of the F₁ fault, intersecting industrial fluorite ore bodies with thicknesses ranging from approximately 2.5 to 15.0 meters. This successful case not only provides a significant reference for the application of the CSAMT method in exploring deep ore bodies within hydrothermal fissure-filled fluorite deposits but also highlights the substantial exploration potential in the deeper parts of the study area.