The talks in Argentina come as the two countries have failed to reach any agreement to resolve a dispute that escalated after Trump slapped huge tariffs on Chinese goods, prompting tit-for-tat responses.
"We hope that both sides can work together on the basis of mutual respect, balance, honesty, and mutual benefit and finally find a solution to solve the problem," Wang Shouwen, Chinese vice minister of commerce, said at a press briefing in Beijing.
Think-tank huddle: US-China rivalry defining factor in South Asian stability
Wang said global trade faces a "complex situation", with "unilateralism and protectionism on the rise" creating uncertainty for economic development.
China hopes the G20 will uphold its backing of multilateralism at the summit, which will take place from November 30 to December 1 in Buenos Aires.
Beijing also backs reform of the World Trade Organization (WTO) to enhance its authority and effectiveness, he said.
Trump said on Thursday he was "very prepared" for the meeting with Xi.
Washington has threatened to toughen measures even further if the issue is not resolved before January.
"China wants to make a deal. If we can make a deal, we will," Trump said.
The United States has imposed punitive tariffs on Chinese goods worth $250 billion per year. In retaliation, China imposed tariffs on $110 billion of US goods.
China says US trying to force it to submit on trade as new tariffs kick in
Earlier this month, Xi and Trump discussed the US-China trade conflict, as well as North Korea's nuclear programme, during a phone conversation that Trump called "very good".
Xi said he was "very happy" to talk to Trump again.
But tensions came to the fore again at an APEC summit last weekend, when Xi and US Vice President Mike Pence delivered competing speeches criticising each other's trade and investment practices.
Xi lashed out at "America First" trade protectionism, while Pence warned smaller countries not to be seduced by China's massive Belt and Road infrastructure programme.
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