The talks are being led by Chinese Vice Premier Liu He, US Trade Representative Robert Lighthizer and US Treasury Secretary Steven Mnuchin, and will end on Friday.
"Looking forward to discussions today," Mnuchin told reporters as he left his hotel on Thursday. He did not elaborate further.
Both sides hope to resolve their dispute ahead of March 1, a deadline earlier set by US President Donald Trump to extend tariffs on Chinese goods.
Since July, the United States has imposed tariffs of 25 per cent on $US50 billion worth of Chinese goods and 10 per cent on another $US200 billion worth, with China retaliating in a similar manner.
The US now stands to raise the 10 per cent tariff to 25 per cent.
On Tuesday, however, Trump said he may consider extending the deadline if talks are near conclusion. Trump has repeatedly said he hopes to meet with Chinese President Xi Jinping to finalise a deal.
There are few signs of movement on the thorniest issue - Washington's demand that Beijing scale back plans for government-led creation of global competitors in robotics and other technologies.
China's trading partners say those violate Beijing's market-opening obligations.
China is also accused of intellectual property theft and forced technology transfers.
Chinese leaders have offered to narrow their multi-billion dollar trade surplus with the United States, but baulk at making major changes to development plans they see as a path to prosperity and influence.
