In order to study the evidence of the geothermal water recharge in Tangshan supplied by the extraneous source and the impact of the Nanjing-Jurong intercity rail transit engineering to the geothermal water resource, δ¹⁸O, ⁸⁷Sr/⁸⁶Sr, and hydrochemistry of the geothermal water and underground cold water were analyzed and compared with those of surface water and reservoir water. The results show that the geothermal water in Tangshan is not supplied by local precipitation, but supplied by extraneous water with the characteristics of isotope depletion. The extraneous water flows out at both ends of the Tangshan Mountain along the fault structure after long distance and deep circle and becomes hot springs. The Nanjing-Jurong intercity rail transit engineering will not affect the recharge and runoff of the geothermal water in Tangshan.