Guanzhong Basin in Shaanxi is a typical area with concealed medium-low temperature geothermal resources in China, and has abundant underground hot water resources. In order to study the formation mechanism and heat source conditions of the medium-low temperature geothermal system of Guanzhong Basin, the temperature structure of crust and upper mantle was analyzed by the geophysical method. The results show that the average depths of Moho and Curie surfaces in Guanzhong Basin are 36.6 km and 25.0 km respectively, and the crustal average geothermal gradient is 22.60 ℃·km-1. The crustal temperature is higher than the average value in Xianli fault terrace, Xi’an sag and Gushi sag, which are the tectonic area with better geothermal geological conditions. Underground in Xianyang and Xi’an, there is a southward inclined geotropics in the upper mantle, and there is a hidden high-temperature zone above 1 500 ℃ in the depth of 175 km to the northern side of Xianyang. Above the high-temperature zone, Moho and Curie surfaces uplift with high geothermal gradient, forming a high-temperature basement, heating the groundwater in the sedimentary strata. Between Fuping and Weinan, there is a “sinking” low-temperature zone in the upper mantle, and there are high-temperature areas greater than 1 450 ℃ at the depth of about 175 km corresponds to the southern and northern sides of the “sinking” low-temperature zone. Above the high-temperature areas, Moho and Curie surfaces also uplift to form a heat accumulation center, providing stable heat source conditions for surface geothermal resources. Generally, the Cenozoic phreatic water in Guanzhong Basin is heated by mantle heat conduction brought by upper uplift of Curie and Moho surfaces, and the thermal material uplifts with Moho and Curie surfaces, which provides stable deep heat source for the basin’s medium-low temperature geothermal fields. The rheological boundary layer of the upper mantle plays an important role in tectonic activities in the research area. The rheological boundary layer is affected by different dynamic forces of the surrounding tectonic belt,which would lead the activity of deep large faults in process of gravity equilibrium adjustment, and then cause the thermal convection of deep and shallow water bodies in the crust along the fault zone, forming a zonal distribution hot spring. [ABSTRACT FROM AUTHOR]