Iowa Governor Terry Branstad believes the US Midwest will attract more Chinese investment and hopes that his state can again export beef to China.

Branstad, US President Donald Trump's pick as ambassador to China, also expressed his hope to go to China soon. The governor made the remarks on Tuesday in his office in Des Moines in a meeting with a Chinese investment delegation.

Branstad, 70, is serving his sixth four-year term as Iowa governor, making him the longest-serving governor in US history.

Branstad has been referred to by President Xi Jinping as an "old friend". The two first met in Iowa in 1985 when Xi visited the US for the first time as a county head in North China's Hebei province. Branstad was serving his first term as Iowa governor then. He hosted Xi when he returned to Iowa as China's vice-president in 2012.

Branstad has led several trade missions over the years to China, which is a key trade partner for Iowa, a major agricultural state and producer of soybeans, corn and pork.

China announced last September that it would lift the ban on the importation of US beef, in effect since 2003 after mad cow disease was found, but the negotiations for technical terms of access to the market have not been concluded, according to news reports.

On Dec 8, Branstad accepted Trump's nomination for the post of US ambassador to China. The nomination awaits confirmation in Congress.

In his nomination statement, Trump said Branstad's decades of experience in public service and his longtime relationship with President Xi and other Chinese leaders make him the ideal choice to serve the job.

"Governor Branstad's decades of experience in public service and longtime relationship with President Xi Jinping and other Chinese leaders make him the ideal choice to serve as America's ambassador to China," Trump said.

"He successfully developed close trade ties with China while serving as chief executive of the Hawkeye State. That experience will serve him well as he represents America's interests and further develops a mutually beneficial relationship with Chinese leadership," Trump said.

"I have known President Xi Jinping for many years and consider him an old friend. I look forward to building on our long friendship to cultivate and strengthen the relationship between our two countries and to benefit our economy," Branstad said in accepting Trump's nomination in December.

The Chinese government reacted favorably to the choice. Foreign Ministry spokesman Lu Kang called Branstad "an old friend of the Chinese people, and we welcome his greater contribution to the development of China-US relations".

Cheng Li, director of the John L. Thornton China Center of the Brookings Institution, told China Daily earlier that the quick pick of US ambassador to China reflects the high attention Trump pays to China.

"By picking his own people to the position, Trump wants to lead China-US relations according to his own thinking," Li said.

"It's a clear sign for Trump to establish good interaction with Xi, so it's very positive in this regard. He not only pays attention to China, but also Xi himself," Li said.

Trump and Xi are expected to meet for their first summit in Florida in April.