Abstract: Canonical correlation analysis was applied to study the relation between soil humus composition and soilacidity in rubber plantations of the west of Danzhou，Hainan province. The results showed that soil humus compositionwas dominated by fulvic acid，followed by humin and humic acid，in 0-40 cm soil layer. The pH value of the rubberplantation soil was 4.32-5.56，indicating that the soil was acidic or strongly acidic，and different rocks and terrain haddifferent effects on soil potential acidity. The results of simple correlation analysis showed that soil fulvic acid hadextremely significantly positive correlation（r=0.58）with hydrolytic acidity，soil humin acid had significantly positivecorrelation with pH（r=0.41），significantly negative correlation with hydrolytic acidity（r=-0.39）and exchangeableacidity （r=-0.48）. Canonical correlation analysis showed that humic acid was the main influence factor of hydrolyticacidity，and soil exchangeable acidity was closely related to humic acid and humin.