The best chance to overcome global challenges is to strengthen relations between China and the United States, which is "the most important bilateral relationship in the world", former US treasury secretary Henry Paulson said on Friday.

The summit between President Xi Jinping and US President Barack Obama in California is very important and the two countries' relations are at the best point, Paulson said.

"What they need to do is to build a mutual trust relationship and reach consensus that they want to strengthen the relationship between our two countries."

Paulson is in China to attend the 2013 Fortune Global Forum in Chengdu, Sichuan province, which is scheduled to close on Saturday.

Henry Paulson, former US treasury secretary, speaks at a session of the Fortune Global Forum in Chengdu, Sichuan province, on Friday. XUE YUBIN / Xinhua

Because China and the US are facing many global challenges in common, such as economic issues, environmental issues and diplomatic issues, Paulson said it is pretty clear that the US needs to reset its relations with China.

"We get the best chances to success, if our two countries are working together. Of course, if we are not, it's going to be very difficult," he said.

Paulson also said the two governments should seize the opportunity to develop an affirmative agenda on market opening, greater protection for bilateral investment, increased cooperation in addressing global climate and energy challenges, as well as on cyber security, including protecting companies from intellectual property theft.

Last year, China surpassed the US to become the world's biggest trading nation as measured by the sum of exports and imports of goods, Bloomberg reported in February.

China and the US are each other's largest trade partners. China-US trade reached $484.6 billion in 2012, which is about 200 times the figure when the two sides established diplomatic relations in 1979.

He said the cornerstone of relations has always been economic.

Paulson expected the tones and objectives for China-US cooperation can be set at the top and economic negotiators from both countries can get some significant achievements during the meeting in California.