Here is your quick guide to the questions you want answering.
Q: Why is the move controversial?
A: The Bill to allow work to begin on the project is not expected to pass through Parliament until next year and critics have vowed to fight it all the way. So they claim the pitch in China is “premature”.
However, Simon Kirby, chief executive of HS2 Ltd - the company set up by the Government to develop the line - said no contracts would be awarded until the legislation had received Royal Assent.
Q: Why Chinese firms?
A: Railway historian and author Christian Wolmar said there are several European countries that also have high speed rail expertise but Chinese firms may be able to carry out the work cheaper.
“China has the biggest system of high speed trains in the world but France has very well-developed technology and so does Germany and Spain,” he added.
“I don’t see that China has the monopoly on the knowledge of how to build such a system.
“It may be that the Chinese can get the trains far cheaper which is probably why he’s done this.”
Q: But could British companies not build HS2? After all railways were invented in the UK.
A: Mr Wolmar insisted there are a number of engineering firms in this country that would be capable of putting the infrastructure for the high speed train line in place.
“I would expect that the trains would probably come from abroad,” he said.
“But in terms of the engineering and the track we would certainly have a lot of companies that would be able to do that.
“There are a lot of British companies that could do the engineering work so I don’t see why George Osborne has gone to China.”
Q: If the Chinese win all the contracts will that not be bad news for British jobs?
A: Officials insist British firms will not lose out because of the decision to open up the bidding process to international contractors.
“We’ve made it a priority to engage with British firms to ensure they are well-placed to compete for the opportunities offered by HS2,” a Government spokesman said.
HS2 chief executive Simon Kirby said they are seeking to draw on the technical expertise of firms in China - which has the world’s largest high speed rail network - and that the project would create some 25,000 British jobs.
Q: Why is the project controversial?
A: The first phase of HS2, from London to Birmingham, would take nine years to complete and pass through unspoiled countryside and beauty spots in the Chilterns which has sparked bitter opposition by some local councils, campaign groups and MPs.
Camden Council has warned that building a new terminus at London’s Euston station would bring “more than a decade of blight” to the area.
At an estimated cost of £50 billion there are some who argue the funds could be better spent elsewhere.
The project could also face difficulties in its passage through the House of Lords. A report by the House of Lords Economic Affairs Committee said the Government had not yet made a convincing case as to why HS2 was necessary.