The present paper deals with the influence of different physical conditions of three typical red earths in China on the phosphorus self-diffusion.Experiment was made under three moisture levels including about 17,22 and 28% for the latosol;15,20 and 25% for the lateritic red earth;15,20 and 25% for the red earth with low fertility;23,27 and 30% for the uncultivated red earth and four grades of soil bulk densities being 1.20,1.35,1.50 and 1.65 g/cm³ except those of uncultivated red soil.