No agreements have been announced but both governments say they are making progress. That has helped to reassure jittery global financial markets.
Washington is pressing Beijing to roll back industry development plans it says are based in part on stolen technology and that violate its market-opening commitments.
Mnuchin said Tuesday he hoped for “substantial progress” in talks this week.
The secretary said earlier this week’s meeting at a Chinese government guesthouse and another round of talks next week in Washington would help American officials decide whether to recommend President Donald Trump agree to a deal with Beijing.
The U.S. delegation is led by Mnuchin and Trade Representative Robert Lighthizer. The Chinese side is led by the country’s economic czar, Vice Premier Liu He.
Trump raised U.S. duties on $250 billion of Chinese imports last year in response to complaints Beijing steals or pressures companies to hand over technology. Beijing retaliated by imposing penalties on $110 billion of U.S. goods.
The talks also cover exchange rates and possible measures to narrow China’s multibillion-dollar trade surplus with the United States.
The negotiators are still discussing how to ensure that Beijing would adhere to whatever commitments it makes, and whether the Trump administration would keep tariffs on Chinese imports to maintain leverage over Beijing.
Mnuchin told Fox Business Network on Monday that an enforcement mechanism just “needs a little bit of fine tuning.”
U.S. officials and businesses assert that China has failed to keep past promises concerning its trade practices.
Critics worry any agreement might hurt other countries by shifting Chinese demand away from them. They also worry it might marginalize the World Trade Organization, which is meant to enforce free trade rules for everybody.