The 409-km toll-free expressway has linked the two major cities which are also tourist attractions in Tibet, state-run Xinhua news agency reported.
The expressway cuts Lhasa-Nyingchi travel time from eight to five hours at a speed limit of 80 km per hour.
The construction cost 38 billion yuan (USD 5.8 billion), according to the local government.
Most of the expressways in Tibet are also compatible for military equipment, providing advantage for the Chinese military to move its troops and weaponry faster.
The massive infrastructure development in Tibet also prompted India to ramp up infrastructure on its side.
Heavy trucks are temporarily banned from using the Lhasa- Nyingchi expressway, state-run Xinhua news agency reported.
The India-China border dispute covers the 3,488 km-long Line of Actual Control (LAC). While China claims Arunachal Pradesh as South Tibet, India asserts that the dispute covers the Aksai Chin area, which was occupied by China during the 1962 war.(PTI)