Soil acid-base buffer capacity is a considerable indicator of soil resistance to acidification.It is of great significance for preventing red soil acidification and the improvement of soil fertility to clarify the changes in acid-base buffering characteristics of red soil under long-term different fertilizations.Based on a 30-year field experiment on a red soil，the changes in acid-base buffer capacity，cation exchange capacity (CEC) and acidity index of red soil were determined under the treatments of no fertilization (CK)，single application chemical fertilizers (N，NP，NK，PK，NPK)，chemical fertilizers plus straw returning (NPKS)，NPK with organic fertilizer(NPKM) and organic fertilizer alone (M).As compared with no fertilization treatment (16.89 mmol·kg-1·pH-1)，the acid-base buffer capacity of red soil in fertilization treatments significantly increased to 19.08～28.01 mmol·kg-1·pH-1.The highest increase was found in NPKM and M treatments，which increased by 6.53 and 11.12 mmol·kg-1·pH-1，respectively.Soil available phosphorus，CEC，organic matter，available nitrogen，total nitrogen，and total phosphorus were significantly positively correlated with soil acid-base buffer capacity (P<0.01).Long-term application of organic fertilizer to increase CEC and SOM is one of the main reasons for increasing soil acid-base buffer capacity.Long-term application of organic fertilizer not only prevents red soil acidification but also improves soil buffer capacity to acid，which is one of the effective measures to improve the quality of red soil farmland.