Shajiang black soil is a major cultivated soil type distributed in the Huang–Huai–Hai region of China. It is characterized by a heavy clay texture, compact structure, low organic matter content, and poor nutrient availability. In recent years, the acidification of Shajiang black soil has become increasingly prominent due to multiple factors, including long-term intensive fertilization, acid deposition, and nutrient removal by crops. This issue has emerged as one of the key constraints on sustainable agricultural development in the region. Soil acidification not only weakens the buffering capacity and nutrient-supplying capacity of Shajiang black soil but also leads to soil structural degradation, microbial community imbalance, and reductions in crop yield. This review synthesizes current research progress on the acidification of Shajiang black soil, with a focus on its status and characteristics, major driving factors, and underlying mechanisms, as well as commonly applied amelioration and management strategies. Furthermore, it analyzes contemporary research hotspots and future development directions, and proposes a classification-based prevention and mitigation framework centered on optimizing tillage systems, improving nutrient resource management, selecting appropriate soil amendments, and enhancing biological synergistic interactions. This framework can provide scientific guidance for the graded amelioration and fertility restoration of acidified Shajiang black soil.