Chinese Vice-President Xi Jinping has told business leaders in California that a strong China is not a threat but "a positive force for world peace".
Mr Xi, widely considered to be China's leader-in-waiting, was speaking in Los Angeles on the last leg of a week-long US visit.
Earlier he met President Barack Obama at the White House and Defence Secretary Leon Panetta at the Pentagon.
His tour will next take him to Ireland then on to Turkey.
Mr Xi, 58, is seen as being almost certain to succeed China's President Hu Jintao, who must retire as head of the Communist Party later this year and from the presidency in 2013.
He made the closely-watched trip as the guest of US Vice-President Joe Biden, who made a high-profile visit to China in August last year.
Mr Xi told delegates at a trade conference in LA hosted by the Chinese Ministry of Commerce: "A prosperous and stable China will not be a threat to any country. It will only be a positive force for world peace and development."
Earlier, Mr Xi, 58, toured China Shipping at the Los Angeles Port and visited with Mr Biden a school specialising in Asian studies, where he told students that his visit "has been a full success".
Mr Biden later said that while there were disagreements on trade and other issues "there's one thing we absolutely agree wholeheartedly, that the future of the 21st Century is going to be written in large part by how well the United States of America and China meet their mutual responsibilities, for us to co-operate in a friendly way".
During Mr Xi's California visit, US film giant DreamWorks Animation announced a $330m (£210m) joint venture with China - Oriental DreamWorks.
It will give the company access to the Chinese market which Hollywood has struggled to break into, but which as a huge untapped market is where the big movie-makers want to be, the BBC's Alastair Leithead reports from Los Angeles.
For Dreamworks it seems an animated Panda opened doors - the movie Kung Fu Panda 2 was a huge hit across China, where the release of foreign films is limited, our correspondent adds.
In Washington on Wednesday, Mr Xi had called for both countries to "reduce misunderstandings and suspicion" via closer communication.
Relations between the two nations, he said, were at a "new historical starting point", stressing that their intertwined interests were an "unstoppable river that keeps surging ahead".
He also addressed key economic, security and human rights issues that have raised tension in the delicate relationship between the two nations.
While admitting that there was "room for improvement" on human rights, he defended his country's record, saying that China had ''made tremendous and well-recognised achievements in the field'' in the last 30 years.
Hundreds of pro-Tibetan activists have staged protests in Washington and Los Angeles, calling for Tibetan autonomy and improved human rights.