US Commerce Secretary Wilbur Ross on Wednesday said he was optimistic about trade talks between President Donald Trump and his Chinese counterpart Xi Jinping when they meet in November.

The US tycoon regularly bashed China during last year's presidential election campaign, accusing it of unfair trade practices, stealing US jobs and threatening to label it a currency manipulator.

But since taking office his tone has changed and when he met Xi in April he described him as a "good man" who was trying to help rein in North Korea.

Now, the president is set to make his first visit to China as part of a tour that will also take in regional allies Japan and South Korea, with trade one of the top agenda items.

"The very fact that the two presidents are meeting again this time in Beijing is an important fact," Ross told reporters in Hong Kong on Wednesday, after visiting Beijing for talks with Chinese premier Li Keqiang.

"What makes me really optimistic is the good relationship that has developed between the two."

"As for the outcomes of the meeting, the most important thing would be deliverables, specific things, bigger things... that will help to reduce the trade deficit that the US has with China."

Ross described the relationship between the world's two biggest economies as "too lopsided at present", with US trade deficit reaching nearly $350 billion last year.

He added that he made no concessions during his latest trip to the mainland.

US Secretary of State Rex Tillerson will be travelling to China on Thursday for talks on how to defuse the nuclear stand-off with North Korea.

Washington has alternated between criticising and praising Beijing's role in the North Korea crisis, on the one hand welcoming its support for new sanctions but also insisting it must do more to rein in its unruly neighbour.

"We've been trying to go step-by-step gradually increasing the economic pressure on North Korea," Ross said.

"If need be and if nothing else happens in terms of other alternative solutions, you can bet the US will increase the pressure as best it can."