To scientifically evaluate the feasibility of using the species sensitivity distribution method (SSD) for studying the safety threshold value of available Cd in agriculture land soil , the Cd-contaminated farmland in Shangrao City, Jiangxi Province was used as a research object in this study. The present study statistically analyzed the total heavy metal, heavy metal availability content, and heavy metal content in rice grains, and the linear regression equation of total soil Cd - availability content of soil Cd and the SSD method based on logistic function distribution model were used to derive the safety thresholds for the availability of Cd in soils, respectively. The results showed that there was a large range of Pb and Cd exceedances in farmland soils, with 54.70% and 68.38% exceedances at the sites, respectively. The soil Cd availability content was high, with an average value of 0.22 mg/kg, and 34.98% of the sites had brown rice Cd content exceedances, and Cd was the main contaminant in farmland soils and brown rice in this study area. The linear regression equation and soil screening value criteria were used to back-calculate the soil Cd availability content thresholds of 0.149 mg/kg to 0.183 mg/kg in agricultural soils and using a logistic function distribution model to fit an SSD curve based on the available content, the safe threshold value of soil availability Cd to protect 95% of local brown rice from exceeding the standard was 0.160 mg/kg in the study area, respectively. The results further validate that the presumed safe threshold of heavy metal availability content based on the SSD method is more scientific and can be used to guide the safe use of local heavy metal contaminated farmland soils and has reference significance for other acidic soil Cd contaminated areas.