Mr Yang said it was important to build up Africa's infrastructure
China says it will give a $7m (£4.4m) grant to help fund infrastructure development projects in Kenya.
The announcement came at the start of the Chinese Foreign Minister Yang Jiechi's latest Africa tour.
His schedule includes visits to Nigeria, Sierra Leone, Algeria, Morocco and Saudi Arabia.
Kenyan President Mwai Kibaki said China has offered to help develop a second port at Lamu which will be connected to Ethiopia, Southern Sudan and Rwanda.
Correspondents said this would provide a route to export Chinese oil from Southern Sudan.
China will also help upgrade a railroad linking Kenya's Mombasa port and the Ugandan capital, said a statement from President Mwai Kibaki's office.
"For Africa to further take off, it is very important to build up the infrastructure so that African countries can conduct intra-regional trade on a massive scale," Mr Yang told reporters.
In November, China's government said it would offer Africa $10bn (£6.3bn) in concessional loans over the next three years.