In this study, to explore the effects of different cropping systems and fertilization practices on acidification indexes and acid buffering mechanisms in black soil, based on the Northeast Dryland Black Soil Fertility Monitoring Long-term Positioning Experiment Station, soil acidification rate (SAR) and soil acid-neutralizing capacity (ANC) under following seven treatments were investigated: continuous soybean with chemical fertilizer (CS), continuous corn with chemical fertilizer (CC), and corn-soybean rotation treatments including both corn and soybean with chemical fertilizer (C_CFS_CF), corn with chemical fertilizer plus straw return while soybean without chemical fertilizer but plus straw return (C_CRS_NOR), corn with chemical fertilizer while soybean without chemical fertilizer (C_CFS_NOF), corn with chemical fertilizer while soybean with 1/2 chemical fertilizer (C_CFS_1/2CF), corn with chemical fertilizer while soybean with dairy manure (C_CFS_DM). Soil ANC and acid-buffering capacity (ABC) at pH 5.0 and pH 4.5 were further calculated by using quadratic curve fitting model as references. The results showed that the change of SAR ranged from –0.019 – –0.097 DpH/a compared to the background pH after 9- and 10-year experimentation. Changes of SAR were lowest under C_CFS_DM in both two years (–0.021 and –0.019 DpH/a). Moreover, soil ANC_pH5.0 in 9^th year was 1.11–1.77 times compared with in 10^th year under C_CFS_CF, C_CRS_NOR, C_CFS_NOF, C_CFS_1/2CF, and C_CFS_DM. The trends of ANC_pH4.5 was consistent with ANC_pH5.0. Variation partitioning analysis showed that soil organic matter (SOM) and the sum of exchangeable base (SEB) were the main factors affecting the changes in soil ANC, and both explained 63.44% and 43.67% of soil ANC and ABC variations after 9 and 10 years, respectively. In conclusion, chemical fertilizer application decreased soil ANC and accelerated soil acidification, while organic fertilizer application increased soil ANC by increasing SOM and SEB.