In response to the complex geological and structural characteristics, as well as the difficulty of construction, of the underground powerhouse cavern group in the TB hydropower Project, the main construction techniques was summarized. The results show that the main construction technologies for the underground powerhouse cavern group include excavation technology for rock wall beams, deep hole pre splitting excavation technology for high side walls, one hole to bottom fine blasting technology, reserved rock cover method technology for the main powerhouse, slag removal technology for inclined shaft small excavators, rapid protection technology for secondary deformation cracking and block falling of large caverns, rope saw cutting technology for ventilation shafts of turbine oil depots, inclined shaft concrete sliding mode construction technology, high flow self compacting expansive concrete construction technology, plain concrete construction technology for water transmission and power generation system frame structure without decoration, circular and turning technology for pressure steel pipe tunnels, and intelligent welding technology for pressure steel pipes. In the intelligent construction process of underground powerhouse cavern group, a smart construction management platform was established using BIM and IoT technology, achieving refined management and intelligent control of construction technology.