3minutes - Source: BBC
Tuesday's launch will allow China to no longer rely on the US government-owned Global Positioning System (GPS).
The $10bn (£8bn) network is made up of 35 satellites and provides global navigation coverage.
It comes as tensions between Beijing and Washington are increasing over the coronavirus, trade and Hong Kong.
The launch had been scheduled for last week but was delayed after technical problems were found with the rocket in pre-launch tests.
The third version of the Beidou Navigation Satellite System (BDS) offers an alternative to Russia's GLONASS and the European Galileo systems, as well as America's GPS.
Future plans promise to support a more accessible and integrated system scheduled to come online by 2035 with BDS at its core.
The first version of BeiDou, meaning "Big Dipper," was decommissioned in 2012.
China's space programme has developed rapidly over the last 20 years as Beijing has provided significant funding to develop the country's own high-tech systems.
In 2003, China became only the third country to launch its own crewed space mission. Since then it has built an experimental space station and sent two rovers to the moon.
The moves are seen as preparation for a permanent space station, a potential crewed flight to the moon, and a possible first attempt to send an orbiter and rover to Mars.
That would make China a serious contender to America in space exploration.
US-China strained relationsThe relationship between Beijing and Washington has become increasingly strained over several issues since the start of this year.
US President Donald Trump and his administration have repeatedly criticised China over its handling of the coronavirus outbreak - the virus first emerged there in December.
In response to a new Hong Kong security law pushed by Beijing, the US president last month announced that he will end preferential treatment for the city in trade and travel.
This week the relationship between the US and China has come under increasing scrutiny after former National Security Adviser John Bolton said in his new book that Mr Trump sought help from Chinese President Xi Jinping to win re-election.