"The extension of the talks indicates that both sides are serious about this consultation", Chinese Foreign Ministry spokesman Lu Kang said of negotiations.
In a statement, the office of U.S. Trade Representative Robert Lighthizer said the two sides considered ways to "achieve fairness, reciprocity and balance in trade relations".
The talks "enhanced mutual understanding, and established a foundation for solving, each other's concerns", said the statement, stressing that both sides agreed to maintain close communication, while providing few other details.
Trump and Xi have given their officials until March 1 to reach an accord on "structural changes" to China's economy on issues such as the forced transfer of American technology, intellectual-property rights, and non-tariff barriers.
Oil prices rose by around one per cent on Wednesday, extending gains from the previous session on hopes that Washington and Beijing may soon resolve trade disputes that have cast a dark shadow over the global economy.
The results of the talks would be analysed at a separate meeting between United States trade representative Robert Lighthizer and Chinese Vice-Premier Liu He.
Washington has presented Beijing with a long list of demands that would rewrite the terms of trade between the world's two largest economies. If a "REAL" deal with China is possible, the USA will "get it done", Trump tweeted shortly after his dinner with Jinping last month. Japan's Nikkei 225 gained 1.1 percent and the Hang Seng in Hong Kong rallied 2.3 percent.
But it also said any deal with China must be followed up with ongoing verification and enforcement. "That's really good for the cost of money and taking some further headwinds out of the USA dollar", he said.
"It seems there have been no fist fights internally between the two delegations", a person familiar with the progress of the talks told CNN on Tuesday, describing them as "constructive".
In what was widely seen as a goodwill gesture, China on Tuesday issued long-awaited approvals for the import of five genetically modified crops, which could boost its purchases of USA grains as farmers decide which crops to plant in the spring.
Chinese officials have suggested Beijing might alter its industrial plans but reject pressure to abandon what they consider a path to prosperity and global influence. Following the economic summit, Vice Premier Liu He is expected to visit Washington, D.C., where he will meet with US trade negotiators led by Robert Lighthizer.
Oil also caught investors' attention after U.S. crude and Brent jumped overnight, helped by optimism over easing Sino-U.S. trade tensions, while OPEC-led crude output cuts also provided support.
On Monday, Chinese importers made another large purchase of U.S. soybeans, their third in the past month.
U.S. Undersecretary for Trade and Foreign Agricultural Affairs Ted McKinney walks into a hotel after a second day of meetings with Chinese officials in Beijing, Tuesday, Jan. 8, 2019.
If talks continue to go well, a cabinet-level meeting is likely to happen before the end of the month.
United States companies also want action on Chinese policies they complain improperly favor local companies.