Cultivated soils with granite and quaternary red earth parent were collected to compare the differences in soil physicochemical indicators under strongly acidic（pH＜5.0）and acid（5.0 ≤ pH＜6.5）conditions，and correlation analysis and redundancy analysis were applied to investigate the differences and the factors influencing acidification in the two types of red soils. The results showed that under strong acid conditions（pH＜5.0），the pH values of the two red soils were 4.85±0.11 and 4.60±0.43，respectively，without significant difference. However，the contents of exchangeable acid，CEC and free ferric oxide in the parent soil of quaternary red earth were significantly higher than those in the parent soil of granite，while the organic matter contents，exchangeable Mg²⁺ content and salt base saturation were opposite. Under acidic conditions （5.0 ≤ pH＜6.5），the pH values of the two parent soils were 5.37±0.33 and 5.48±0.48，respectively. The contents of calcium carbonate and free ferric oxide in the quaternary red earth soil were significantly higher than those in the granite red soil. The pH of the two red soils was positively correlated with total amount of base ions，exchangeable Ca²⁺ content， exchangeable Mg²⁺ content，calcium carbonate and base saturation，and negatively correlated with exchangeable acid， exchangeable H⁺ content and exchangeable Al³⁺ content.