The centre, constructed by the China Atomic Energy Authority (CAEA) and the US Department of Energy, is able to train about 2,000 nuclear-security staff for China and other nations in the Asia-Pacific region every year, CAEA chair Xu Dazhe said.
Construction of the centre, which is the largest nuclear programme to have direct the Chinese and US investment, began in December 2013.
Top Chinese, US and IAEA (International Atomic Energy Agency) officials attended today's the event.
Under the agreement, the centre, which is located in Fangshan District, Beijing, is run and administered by China, while the US is responsible for providing nuclear-security equipment.
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According to the CAEA, the site will become a centre for international exchanges and cooperation on nuclear security, the demonstration of advanced technology, testing and analysing.
Commenting on its significance, China's Foreign Ministry spokesman, Lu Kang said it was constructed one year ahead of schedule and demonstrated close cooperation between China and US.
Earlier President Xi Jinping said the centre will be developed as the largest and the most advanced in the nuclear field.
The centre is a significant achievement in China-US nuclear security cooperation, and will boost cooperation in the Asia-Pacific region and the world, Wang Yiren, deputy director of the CAEA said.
It will also promote the peaceful use of nuclear power, Wang, who is also deputy head of the China's State Administration of Science, Technology and Industry for National Defence said.
The centre came as China is massively expanding its nuclear reactor network.
China currently has 30 operational nuclear power generating units, with a total installed capacity of 28.31 GW. It also has 24 units with a total installed capacity of 26.72 GW under construction, ranking first in the world.
As planned, China's installed nuclear power capacity will reach 58 GW with an additional 30 GW under construction by 2020.
"Construction projects for six to eight new generators are expected to begin each year from 2016 to 2020," Wang said.