From the BBC (link):
Beijing is desperate for oil and natural resources to fuel its booming economy. And some African nations have plenty of both.
China is also keen to find new markets for its booming factories which are churning out everything from shoes and cars to textiles and TV sets.
During the Cold War, Chairman Mao established links with many developing countries in Africa.
But now the old ties of communism are being replaced by capitalism.
See also “China-Africa trade prospects look promising” from People’s Daily and “President Hu Jintao of China Visits Nigeria” from Nigeria First. For more background, see “China’s Influence in Africa: Implications for U.S. Policy” (download PDF file).