The British government is in "preliminary discussions" with the part state-owned China Railway Construction Corporation (CRCC) to help build the controversial HS2 high-speed link, according to the Department of Transport.
"The DfT is always keen to learn from the experience of others and to consider approaches that offer value for money to the taxpayer," said a ministry official, confirming reports in Saturday's Financial Times.
The department added that no "concrete commitments" had been made.
London finally approved the new high-speed railway line on Tuesday, with full construction work to begin in April following years of delays, after Prime Minister Boris Johnson backed the project.
He said the entire HS2 line linking London to central and northern England would go ahead, rejecting criticism of a ballooning price tag and impact on the environment.
"If we start now, services could be running by the end of the decade. So today... the cabinet has given high-speed rail the green signal," he told the House of Commons.
The CCRC wrote to rail chiefs last month in a letter seen by Building Magazine saying it could construct the line five years earlier than scheduled for a much reduced price.
"We are certain that we can offer a cost that is significantly lower than the projections we have seen," the magazine quoted the letter as saying.
"The advantages are too great, in our opinion, too great to dismiss on the basis that there are obstacles to overcome.
"You will find that the Chinese way is to seek solutions, not linger on obstacles and difficulties," it added.
An independent review into the scheme, currently the largest infrastructure project in Europe, estimated it could cost more than £100 billion ($129 billion, 118 billion euros).
But Johnson hopes HS2 would help rebalance the economy away from London and the south-east of England, and reduce climate emissions by persuading car drivers to take the train.
Chinese involvement in a key infrastructure project would be hugely controversial, given the furore surrounding Britain's decision to allow telecoms giant Huawei into the country's 5G network.
The decision left the United States "disappointed" after it called for a total ban.