With his approval ratings dented by his entanglement in the Middle East, Trump's hotly anticipated trip to China - the first by a US president to America's main strategic rival since his last visit there in 2017 - has taken on added significance.
Joining him on the trip are a group of chief executives looking to resolve issues with China, including Elon Musk and Nvidia's Jensen Huang, a late addition. Trump has said his first request to Xi will be to "open up" China to US industry.
The pomp-filled summit began at Beijing's imposing Great Hall of the People on Thursday when Xi greeted Trump on the red carpet, with the leaders shaking hands and smiling warmly.
Chinese troops goose-stepped to revolutionary anthems in front of the visiting US president, while schoolchildren waving American and Chinese flags cheered as the two leaders strolled past, Trump occasionally patting Xi on the back.
"You're a great leader, sometimes people don't like me saying it, but I say it anyway," Trump told Xi as they sat across from each other, flanked by their delegations.
"There are those who say this may be the biggest summit ever ... It's an honour to be with you. It's an honour to be your friend and the relationship between China and the USA is going to be better than ever before," Trump said.
Xi told Trump: "Each country's success represents an opportunity for the other, and a stable China-US relationship benefits the entire world. When we co-operate, both sides benefit; when we confront each other, both sides suffer."
This week's meetings will provide plenty of face time between the leaders: they are scheduled to hold talks at The Great Hall of the People, tour the UNESCO heritage site Temple of Heaven and attend a state banquet on Thursday, before taking tea and lunch together on Friday, according to the White House.
Trump enters the talks with a weakened hand. US courts have hemmed in his ability to levy tariffs at will on exports from China and other countries.
The Iran war has also boosted inflation at home and escalated the risk that Trump's Republican Party will lose control of one or both legislative branches in November's midterm elections.
Though the Chinese economy has faltered, Xi does not face comparable economic or political pressure.
Nevertheless, both sides are eager to maintain a trade truce struck last October in which Trump suspended triple-digit tariffs on Chinese goods and Xi backed away from choking global supplies of rare earths, vital in making items from electric cars to weapons.
They are also expected to discuss forums to support mutual trade and investment and dialogue on AI issues.
Washington looks to sell Boeing airplanes, farm goods and energy to China to cut a trade deficit that has long irked Trump, while Beijing wants the US to ease curbs on exports of chipmaking equipment and advanced semiconductors, officials involved in the planning said.
Aside from trade matters, Trump is expected to encourage China to convince Tehran to make a deal with Washington to end the conflict.
US Secretary of State Marco Rubio told Fox News aboard Air Force One that it was in China's interest to help resolve the crisis as many of its ships are stuck in the Gulf and a slowdown in the global economy would hurt Chinese exporters.
For Xi, US arms sales to Taiwan, the democratically governed island claimed by China, will be a top priority.
China reiterated on Wednesday its strong opposition to the sales, with the status of a $US14-billion ($A19 billion) package awaiting Trump's approval still unclear.
With AP
