To explore and know the health risk of farmland polluted by Cd and its main factors to control rice uptake of Cd, the correlation between available Cd in soil and Cd in rice seeds and its impacting mechanism were studied in typical areas from the Jiangsu Province. By systematically analyzing relative regional eco-geochemical survey data, 1330 sets of rice-soil samples were collected according to the difference of Cd distribution and its geochemical background in the typical areas of Jiangsu_^, rice plant, and Cd, Zn, Se, pH, TOC (Total Organic Carbon) and CEC (Cation Exchange Capacity) in soil and Cd in rice seeds were determined by advanced testing methods such as ICP-MS, etc. And the available Cd in soil was determined by calcium chloride extraction. The main research results are as follows:1)The Cd concentrations in rice were from 0.0053 mg.kg_^-1 to 2.58mg.kg_^-1, and its mean value was 0.478 mg. kg_^-1. The available Cd concentrations were from 0.0018 to 1.44mg.kg_^-1, Mean=0.265, and the total Cd concentrations in soil from 0.13 to 30.0mg.kg_^-1, Mean=2.11, the qualified rate of repeated detect of the available Cd reached 90.7%. 2) there is a significant positive correlation between the available Cd and Cd in soil, and there are the significant negative correlation between the available Cd and pH, TOC, CEC in soil under some limited conditions , such as TOC ranged 2～3%, or Cd concentrations less than 0.9 mg.kg_^-1, or Cd availability ranging from 0.3 to 30%, etc., and their correlated coefficients( r) were respectively in turn 0.94, -0.62, -0.54, -0.64, and their weights of correlated coefficients were respectively 0.33, 0.47, 0.49, 0.53. 3) there was a significant positive correlation between Cd in rice seeds and the available Cd in soil and its correlated coefficient is 0.54 with 1.0 weight of correlated coefficient at same time, and the positive correlation between Cd in rice seeds and the available Cd in soil were better than that between Cd in rice seeds and Cd in soil at most cases, but this result was opposite when pH less than 5.5. 4) the positive correlation between the available Cd and Cd in soil were better than that of Cd in rice and Cd in soil, the former of correlated coefficients ranging from 0.32 to 0.9, and the latter of correlated coefficients ranging from 0.25 to 0.84. 5) there are the negative correlation between Cd in rice seeds and pH, TOC and CEC in soil, their correlated coefficients are generally ranging from -0.31 to -0.65, and its weights of correlated coefficient are generally ranging from 0.1 to 0.5. 6) it is possible that correlation between the available Cd and Zn, Se in soil is being transferred to rice seeds, and these positive correlation between TOC and CEC, between TOC and pH, and between pH and CEC can impact on distribution of the available in soil and the Cd in rice and their correlations at a certain condition. The main geochemical factors to impact Cd concentration in rice seeds should be the available Cd, Cd and pH in soil. 7) there are higher ecological health risks in Cd contaminated areas, because of Cd content exceeded the standard in soil and rice, its main proof included following: Cd non-carcinogenic health risk index HQ average value increased by 17 times, Cd carcinogenic health risk index CR average value increased by 85 times, mean Cd content in human hair increased by 1.09 times, and there was a significant amplified effect of health risk as to Cd pollution. The above stated studied results will deepen our accurate understanding of the available Cd in soil, the Cd in rice seeds and its geochemical controlled factors, and provide effective help and new scientific clue for the prevention and control of Cd pollution risk.