Abstract: The heavy metal pollution in cultivated soil has become one of the outstanding shortcomings that restrict the healthy development of green agriculture. Super-stable mineralized materials (LDHs) is a new layered composite metal hydroxide, which has high efficiency and stability in the field of soil remediation because of its hierarchically layered structure, high particular surface area, and exchangeable interlayer anions. Exploring the effects of LDHs on heavy metal Cd in soils-crop systems can provide scientific basis for the safe utilization of Cd contaminated farmland. Taking Cd-contaminated red paddy soil as the research object, using the indoor amaranth pot experiment method, five different dosage of LDHs (0, 2 g·kg⁻¹, 5 g·kg⁻¹, 10 g·kg⁻¹ and 20 g·kg⁻¹) were set to study the effects of LDHs on soil pH, available Cd content in soil and Cd content in amaranth. The results showed that: compared with CK, the soil pH value is significantly increased by 0.85 ~ 3.54 (P<0.05) after LDHs application, and increases with the increase of application rate. The content of available Cd is significantly decreased by 58.5% ~ 99.6% (P<0.05), and decreases with the increase of application rate. When the application rate is 2 g·kg⁻¹, there is no significant difference between the Cd content in aboveground part of amaranth and CK. When the application rate is ≥5 g·kg⁻¹, the Cd content in aboveground part of amaranth decreases with the increase of the application rate, by 52.5% to 87.8% (P<0.05). The content of Cd in underground parts of Amaranth is significantly lower than that of CK, decreases by 45.3% to 85.5% (P<0.05), and exhibits a decreasing trend with the increase of application rate. The bioconcentration factor (BCF) of amaranth is consistent with the above change rules. There is a significant negative correlation between soil pH and soil available Cd content, BCF_shoot-soil and BCF_root-soil; while soil available Cd content is positively correlated with BCF_root-soil and BCF_shoot-soil. LDHs could significantly increase soil pH value and reduce soil Cd activity, thus reducing the migration and enrichment of Cd in plants, and having a good control effect on Cd in soil-crop system, which could be effectively applied to the passivation and remediation of Cd-contaminated farmland. Combined with the production cost and remediation effect, the appropriate application rate is 10 g·kg⁻¹.