To investigate the characteristics and differences in cadmium (Cd) enrichment capacity between rice and wheat grains, along with the key factors influencing grain Cd accumulation. Continuous in situ remediation experiments were conducted in farmland with varying of Cd contamination levels, and by cultivating different genotypes of wheat and rice, this study systematically compared the effects of soil conditioners application and genotype differences on Cd accumulation in wheat and rice grains. The results showed that application of soil conditioners (SCM1, SCM2, OM, BC) elevated soil pH and effectively reduced available Cd content in soil, and consequently decreased Cd in grains. Under soil total Cd content ranging from 0.66 to1.13 mg/kg, grain Cd concentration of all wheat genotypes (0.08–0.47 mg/kg) and the bioconcentration factor (BCFCd: 0.16–0.27) were significantly higher than those in rice grains (Cd: 0.011–0.084 mg/kg; BCFCd: 0.010–0.058), indicating a stronger Cd accumulation capacity in wheat than rice. Multiple regression analysis revealed a significant negative correlation between grain Cd enrichment and soil pH, and identified soil available Cd levels as a critical factor affecting Cd accumulation in grains. These findings provide a theoretical foundation and practical reference for the safe utilization of Cd-contaminated farmland.