The CIIE, a significant move by the Chinese government to further open the Chinese market, has attracted about 2,800 exhibitors from over 130 countries and regions.
The expo has been met with some foreign scepticism, with Washington snubbing the gathering by not sending high-level representation, instead calling on China to change "unfair" trade practises.
"Actively expanding imports is not a temporary measure of China, but it's long-term, future-oriented strategy to promote the joint development of the world's nations", Xi said.
"China's economy is truly performing well within the reasonable range, giving us a solid foundation for delivering the development goals for the whole year", Xi said.
"It is important for all countries to open wider and expand space for mutually beneficial cooperation".
In speeches made over the last two months, Ma has said that the USA will "suffer more" from the dispute, stating that the U.S. economy had benefited from its trade relationship with China.
China's shift to an import model is "going to be a huge pain for a lot of businesses, but it's also going to make a good opportunity for a lot of consumers", he said.
In a sign the trade row is starting to bite, export orders to the United States recorded during China's biggest trade show, the Canton Fair in October, dropped 30.3 percent from a year earlier by value, the fair's organiser China Foreign Trade Center said.
On Monday, Ma also stated that manufacturing was no longer creating jobs in China, pointing to the rise of services that will help create employment.
No officials from the United States - China's top trading partner - will be present as their trade dispute rages, but over 100 US firms will be exhibiting their wares.
China is under pressure from Trump and elsewhere to wind back its US$423 billion goods trade surplus with the world, and Xi has already pledged that the country will import US$24 trillion dollars of goods from overseas over the next decade and a half. Trump has been insisting that China should cut down United States dollars 375 billion trade deficit by providing more access to the American goods by ensuring IPR (Intellectual property rights) protection.
However, the European Union said in the run-up to the import expo that it would have to go beyond tariff adjustments.
The company will not only set up a silk processing factory at the Export Processing Zone in Athi River but will also establish a silk farm. China, the top global exporter, plans to become a major importer.
The CIIE only hosts foreign enterprises that are seeking to sell to the Chinese market, and no Chinese manufacturers are permitted to take part in the expo. Beijing has mobilised large state-owned companies under its control to send purchasers to the expo and expects altogether 150,000 professional buyers-mainly Chinese-to attend.
As this year marks the 40th anniversary of the country's reform and opening-up policy, the Asian power, by holding the expo for imports, will try to brush aside criticism that Chinese markets are closed given that they are mainly controlled by the government.
All major countries in the world including U.S. and India, have massive trade deficits with China which is the leading exporter of the world.
"These trends point to sectors with particularly strong growth potential, such as household appliances, cars, healthcare, education, recreation, travel and tourism", she said.