【Objective】 Long-term tillage and fertilization accelerate soil acidification of red loam rice. Thus, this study was designed to study the effects of green manure, straw return, and lime combination on the soil acidity characteristics of rice soil and rice yield. 【Method】This study is based on the long-term positioning micro-area experiment started in 2016 to explore the effects of no fertilization (CK), chemical fertilizer (F), chemical fertilizer + milk vetch + rice straw return (GRF), chemical fertilizer + milk vetch + straw return (GRFL) treatment on rice yield and different forms of acid in red soil. The effects of soil salt-based ions and soil acid-base buffer capacity was resolved, and the correlation between soil acid-base buffer capacity, exchangeable acid, organic matter, and exchangeable salt-based ions was investigated. 【Result】 The results for seven consecutive years showed that compared with F treatment, the yield of early and late rice treated by GRF increased by 19.9% and 5.1%, respectively, and the average yield increase rate in 7 years was 12.8% and 5.9%, respectively. The yield of early and late rice treated by GRFL increased by 23.4% and 14.2%, respectively, and the average yield increase rate in 7 years was 11.1% and 8.9%, respectively. During this time, the soil pH of early and late rice treated with CK, F and GRF showed a decreasing trend year by year, while the soil pH value of GRFL treatment showed a trend of first increasing and then decreasing. Compared with F treatment, GRF and GRFL treatment significantly improved the exchangeable K, the total amount of exchangeable salt-based ions and the acid-base buffer capacity of early and late rice soil, and there was no significant difference between GRF and GRFL treatments, but all indexes of GRFL treatment showed an improvement trend. Correlation analysis showed that pH was negatively correlated with exchangeable acidity and exchangeable H+ (P < 0.01) and positively correlated with acid-base buffer capacity, exchangeable Na+, exchangeable Mg2+, and the total amount of exchangeable salt group ions (P < 0.01). Also, the soil acid-base buffer capacity was mainly related to the exchangeable acidity, exchangeable H+, exchangeable Na+ and exchangeable Mg2+. In addition, rice yield was related to soil acidity properties and nutrient effects, and the soil acidity properties had the greatest impact. 【Conclusion】 The results showed that rolling green manure and straw returning to the field could effectively alleviate the acidification of paddy soil and improve rice yield, and the addition of lime could enhance its effect, and the exchangeable acidity, exchangeable H+, acid-base buffer capacity, exchangeable Na+, exchangeable Mg2+, and total exchangeable salt-based ions were the main factors affecting soil pH.