In recent years，the pH value of Eucalyptus plantation soil in Guangxi decreased obviously，and soil acidification has gradually become the main obstacle factor restricting the soil quality of Eucalyptus plantation.However，soil acidification status of Eucalyptus plantation soil cannot be evaluated from the perspective of active acid alone，and soil acid control technology of Eucalyptus plantation is lacking.Based on the soil acidification characteristics of Eucalyptus plantation in Guangxi red soil region，the acid control system was constructed and the acid control effect of each acid control system was compared to provide a scientific basis for alleviating soil acidification of Eucalyptus plantation.Soil samples of Eucalyptus plantation in Guangxi red soil region were collected to determine pH value，exchangeable acid content and acid buffer capacity，and to analyze the distribution characteristics of free acid and potential acid in soil.With three organic acid control agents(humates，xanthulates and amino oligosaccharides)and two inorganic buffers(potassium dihydrogen phosphate and dipotassium hydrogen phosphate)as alternative materials，the organic-inorganic acid control systems were constructed by pairwise collocation.Three kinds of organic-inorganic acid control systems with the best buffer capacity were selected，and the dynamic effects of three kinds of acid control systems on soil acidity were measured by comparison of acid control effects.The results showed that the pH value of strongly acidic soil of Eucalyptus plantation in Guangxi red soil region ranged from 4.50 to 4.85，the content of exchangeable Al3+ was 2.60-4.30 cmol/kg，and the average buffer capacity of soil acid was 38.90 mmol/kg.The three organic-inorganic acid control systems with the best buffer performance were 5∶1 amino oligosaccharides+dipotassium hydrogen phosphate，10∶1 xanthohuate+potassium dihydrogen phosphate and 10∶1 humate+potassium dihydrogen phosphate.After 30 days of application of the above three acid reduction systems，compared with the blank control，soil pH value increased by 1.17，0.98 and 0.73 units，respectively，increasing by 25.36%，21.24% and 15.82%.The content of exchangeable Al3+ decreased by 2.7，0.8 and 2.2 cmol/kg，respectively，by 74.07%，24.07% and 62.04%.The soil of Eucalyptus plantation in the red soil region of Guangxi is strongly acidic.and it is slightly sensitive to exogenous acid and susceptible to acid damage.Exchangeable Al3+ is the main exchangeable acid，and its content is higher than the critical point of crop aluminum stress.Eucalyptus growth may be subjected to aluminum stress.Considering the effects of three acid control systems on soil acidity，the combined application of amino oligosaccharides and dipotassium hydrogen phosphate was the best for acid control of Eucalyptus plantation soil in Guangxi red soil region，and the results of subsequent field trials need to be further verified.