Pot experiments were conducted to study effects of addition of EDTA-Na₂ only, NTA only and both in combination, separately, on growth and heavy metal accumulation of castor seedlings, growing in a substrate of Pb-Zn tailings and soil in ratio of 1:1. Results of the experiments show that biomass and root morphological parameters of the castor seedlings decreased significantly with the addition of chelating agents. The decrease in the number of root tips was the most significant. Comparison with the control demonstrated that the difference reached extremely significant level ( p <0.01). Addition of the chelating agents reduced chlorophyll a, b, and a+ b significantly in castors ( p <0.05), especially chlorophyll b. The activities of SOD (Superoxide Dismutase), CAT (Catalase) and POD (Peroxidase) in leaves of the castor seedlings were also affected, ascending first and then descending with the increasing EDTA application rate. The addition increased generally Pb and Zn contents in the castor seedlings, with Pb in particular, demonstrating that it significantly enhanced the plant’s capacity of accumulating Pb and Zn, especially Pb, and of transferring Pb and Zn from roots to shoots, with translocation coefficient reaching the peak when 3 mmol kg^-1 EDTA and NTA was added. Castor is relatively high in tolerance to Pb and Zn and in capacity of accumulating the two, so it can be used in the study on phytoremediation of waste lands of Pb-Zn tailings.