The Yangbajing geothermal field located 94 km northwest of Lhasa, the capital of the Tibet Autonomous Region, China is the first high-temperature hydrothermal convective geothermal field in China. Generalized definition of hot dry rock system mainly emphasizes the reservoir is comprised of hot fractured rocks, and whether there is pre-existing water is not the key point, so the naturally hot fractured granite reservoir at Yangbajing geothermal field might be taken the consideration into the hot dry rock resource type. Development of deep high-temperature heat reservoir at Yangbajing geothermal field has very important significance for capacity expanding and sustaining of the ground power plant. The geological exploration found that there is a fractured granite heat reservoir with an average temperature of 248ºC at depth of 950-1350 m at well ZK4001 in the north of the geothermal field. A simplified conceptual model of the 950-1350 m reservoir is established based on all the existing geological data, and the electricity generation potential from this fractured granite reservoir by geothermal water mining through a single horizontal well is numerically simulated by the scientists from Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences.