The conceptions and present conditions on site productivity decline of timber plantation in China and other countries are reviewed in this paper.Then,its causes are analysed from biological properties of species,soil intoxication,soil acidation,community struction,ground clearance,site preparation,tending and rotation respectively.On basis of above analyses,control studies of site productivity decline are discussed on mixture,fertilizer,sivilcultural system reformation,shifting cultivation,change of community struction.Finally,new advance in research on site productivity decline of timber plations is summed up and the trend of its research is pointed out.