Chancellor George Osbourne opened the bidding during a visit to China, where he is promoting the Northern Powerhouse.
At least seven new contracts worth £11.8 billion will be opened up to companies for phase one of the construction between London and Birmingham.
Mr Osbourne also announced plans for a new 'HS2 partnering day' between British and Chinese firms to explore joining up on bids for contracts.
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Construction on phase one of the project is due to begin in 2017.
Work is already underway to redevelop East-West rail links.
Transport Secretary Patrick McLoughlin said: "HS2 provides an excellent opportunity for businesses across the UK with 25,000 jobs created during construction and 3,000 when up and running.
"The start of the procurement process for these significant contracts is a major step towards construction on HS2 getting underway in two years’ time and a massive opportunity to help rebalance our economy long before the trains start running in 2026."
HS2 Chief Executive Simon Kirby added: "The start of the civil engineering bidding process is a major milestone for HS2 as we continue to move towards the start of construction in 2017.
"Over the next decade, the winners of these contracts will go on to build 230km of bridges, tunnels and earthworks and create thousands of jobs across the construction industry."
(LM/CD)
