China must drop its illusion that its relations with the United States will automatically improve under President-elect Joe Biden's administration, a Chinese government adviser has said, adding that Beijing should be prepared for a tough stance from Washington.

Zheng Yongnian, the Dean of the Advanced Institute of Global and Contemporary China Studies, a Shenzhen-based think tank, has said that the Chinese government should utilise every opportunity to mend ties with the US, South China Morning Post has reported.

"The good old days are over... the Cold War hawks in the US have been in a highly mobilised state for several years, and they will not disappear overnight," Mr Zheng said in an interview on the sidelines of the Understanding China Conference in Guangzhou recently.

Mr Zheng, who attended a symposium hosted by President Xi Jinping in August to offer advice on China's long-term strategy, said there was now a bipartisan consensus in the US on containing China.

Mr Zheng said President-elect Joe Biden might take advantage of the public resentment towards China after he entered the White House. "American society is torn apart. I don't think Biden can do anything about it," Mr Zheng said.

"He is certainly a very weak President, if he can't sort out domestic issues, then he will do something on the diplomatic front, do something against China. If we say Trump is not interested in promoting democracy and freedom, Biden is. (President Donald) Trump is not interested in war... but a Democratic President could start wars."

The relationship between China and the United States has deteriorated under President Trump over a variety of reasons, including the COVID-19 handling, trade and human rights.

Over 300 separate Bills targeting China have been drawn up by both Democrats and Republicans in the Congress, and the important ones addressing the catastrophes in Hong Kong and Xinjiang enjoyed full bipartisan support. The most potentially effective law, the Hong Kong Human Rights and Democracy Act, which Trump only reluctantly signed, was co-sponsored by Republican Marco Rubio and Kamala Harris, the Democrats' Vice-President-elect.

Chinese foreign policy specialists have said they expect tensions between the US and China to continue under the Biden presidency.

At times during the election campaign, Biden took a tough line on China, calling Mr Xi a "thug".

His campaign also signalled that he will call out China on its repressive policies in the far western region of Xinjiang.

Mr Zheng said China remained resolute in protecting its sovereignty and hoped the next US administration would "meet China halfway".