Abstract: The principle of photocatalysis of p-n type semiconductor composite photocatalysts and its current research progress are reviewed. Based on the p-type semiconductors，the catalysts are divided into four types：CoOx-n-type，CuxO-n-type，NiOx-n-type，and other p-n type semiconductor materials，such as p-n heterojunction photocatalysts and photocatalytical diodes. Finally，some problems in the study of p-n type semiconductor composite photocatalysts are indicated and a brief discussion about the future research is given.