An agreement was signed at the APEC Summit in Papua New Guinea, where China also agreed to defer Tonga's loan repayments for five years.
China also signed off on a $US14 million aid grant for a yet to be finalised project.
Lopeti Senituli, a political adviser to Tongan Prime Minister 'Akilisi Pohiva, says Tonga will benefit from Belt and Road.
"We are already exporting squash, we are also exporting our sea cucumber, but we are also hoping to expand that to other agricultural and marine resources to China," said Lopeti Senituli.
Mr Senituli said he was confident Tonga would be able to meet its loan repayments to China in time for the 2021 deadline.
Xinhua reported on Friday that nine Tongan sports teams, including around 100 athletes and coaches, would receive training in China as part of a new two-year aid project.