Chinese Foreign Minister Yang Jiechi has arrived in Zimbabwe at the start of a five-nation tour of Africa.
He described the country as a "good brother" to China, ahead of an expected meeting with President Robert Mugabe.
There have been reports China has agreed a $10bn (£6bn) trade deal with Zimbabwe.
China's ties with regimes subject to sanctions by the West has been a source of controversy but China has defended its role on the continent.
"China is ready to work with Zimbabwe to further enhance political mutual trust, expand mutually beneficial cooperation and steadily elevate our friendship and cooperation," said Mr Yang on his arrival.
"China sets store by its relations with Zimbabwe and regards Zimbabwe as a good friend, good brother and good partner."
He will hold separate meetings with President Robert Mugabe, Prime Minister Morgan Tsvangirai, and his counterpart Simbarashe Mumbengegwi.
He is then scheduled to open an agricultural research centre at a college outside the capital, said China's ambassador in Harare Xin Shunkang.
Figures from the national statistics agency suggest China exported $159m (£99m) worth of goods to Zimbabwe last year.
The China Development Bank has plans to spend $10bn in Zimbabwe's mining, agriculture and infrastructure sectors, according to comments made several weeks ago by Zimbabwe's investment promotion minister.
China's ties with Zimbabwe, which go back to pre-independence times, have helped protect Mr Mugabe's government at the United Nations.
The Chinese use of its veto in 2008 was "a landmark diplomatic decision where it basically saved Zimbabwe from punitive sanctions instigated by an irate and sulky former colonial power", the Chinese news agency Xinhua quoted Mr Mumbengegwi as saying.
"So, now this visit will give an opportunity for Zimbabweans to finally thank China for this act," he said.
Chinese support for Mr Mugabe is behind the presence of the Zimbabwe leader's daughter at university in Hong Kong, and the controversial visits by Mr and Mrs Mugabe to the former British colony in recent years.
China plans to expand the relationship to "a larger scale, broader scope and higher level", according to a policy paper released by the state information office in December 2010.
Disturbances on Monday highlighted the tensions surrounding foreign investment in the country.
Police made several arrests after youths allegedly linked to Mr Mugabe's Zanu-PF party attacked Chinese, Nigerian and South African stores in Harare.