Abstract: The different formed aluminum in forest soil at two typical acid rain areas were detected.It is shown that the amount of amorphous aluminum and organically bound aluminum are high in both areas,the amount of exchangeable aluminum and weakly organically bound aluminum are relatively low; the exchange ability of aluminum can be weakened by organic ligand;and Al3+ has strong displacement ability to other base cations.The stronger the acidity of soil is,the more the contents of exchangeable aluminum and weakly organically bound aluminum are.The vertical change of exchangeable aluminum and weakly organically bound aluminum in different horizons of soil is in keeping with the change of pH.The method mechanism of oxalate-extractable aluminum needs to be further studied.