"China regards Zimbabwe as a good friend, good brother and good partner," Yang said on his arrival. He will meet separately with President Robert Mugabe, Prime Minister Morgan Tsvangirai, and Foreign Minister Simbarashe Mumbengegwi, the BBC reported.
He also will open an agricultural research site at a college outside Harare, said Chinese Ambassador Xin Shunkang.
Zimbabwe's investment promotion minister has said the China Development Bank plans to invest $10 billion in the mining, agriculture and infrastructure sectors.
China also has shielded the Mugabe government diplomatically at the United Nations.
Its veto at the Security Council in 2008 "saved Zimbabwe from punitive sanctions instigated by an irate and sulky former colonial power" -- Britain -- the Chinese state news agency Xinhua quoted Mumbengegwi saying. "So, now this visit will give an opportunity for Zimbabweans to finally thank China for this act."
A Chinese policy paper issued in December calls for expanding ties with Zimbabwe to "a larger scale, broader scope and higher level."