The main idea behind the expo is to promote China's effort of opening up its trade borders.
China would "foster a world-class business environment" and its doors will open "ever wider", he said.
The richest man of China, who is recently back from its commitment to create 1 million jobs in the United States - blaming the trade war triggered by the us president, Donald Trump - speaking at a round table organized in the framework of this large fair, designed to silence criticism directed at Beijing over its trade policy.
"They should not hold a flashlight in hand, doing nothing but highlighting the weaknesses of others and not their own".
The trade surpluses enjoyed by China are attracting more and more criticism overseas and are at the origin of an escalation of the trade conflict with Washington, which has seen the two parties to impose customs duties, punitive damages of hundreds of billions of dollars of goods.
More than 3,000 companies from over 130 countries have confirmed participation in the enterprise and business exhibitions at the expo, with a total booth area of 270,000 square metres, state-run China Daily reported.
But trading partners and foreign enterprises say he is yet to put his money where his mouth is, and they are exhausted of empty promises.
He said "economic globalization is facing setbacks, multilateralism and the free trade system is under attack, factors of instability and uncertainty are numerous, and risks and obstacles are increasing".
But it adds it is also an worldwide public product provided by China for all the countries in the world discussing about major issues of foreign trade and world economy and improving global economic governance.
Foreign business surveys indicate the playing field is worsening as Xi champions a strong-China message not unlike Trump's "America First" platform.
"(The) Trade war is the most stupid thing in this world", Ma said on Monday at the China International Import Expo here.
China ranks 59th out of 62 countries on openness to foreign direct investment, according to an Organization for Economic Cooperation and Development ranking.
Beijing has touted the first annual import expo as a sign of its willingness to take in more imports and thereby reduce the surpluses.
Washington has snubbed the gathering by not sending high-level representation, instead calling on China to change "unfair" trade practices. Find us on Facebook too!
Both are seen as eyeing new ways into China.
Christoph Matznetter, vice president of the Austrian Economic Chamber, told Xinhua that the Import Expo offers a special opportunity for Austrian companies to showcase their products and services directly to potential buyers in China.
Trump, however, has in recent days raised hopes of a resolution to the trade spat, saying he was optimistic a deal could be reached soon.