Abstract: In order to determine the effect of aging process on the toxicity of exogenous Sb(Ⅲ) in soil, different valence Sb concentrations, extracted concentration of exogenous Sb(Ⅲ) and their effects on growth, fertility, and reproduction of model organism Caenorhabditis elegans after 7 and 56 d aging in Anhui yellow-brown soil and Xinjiang grey dessert soil were tested by chemical analysis and toxicity test of Sb. The proportion of Sb(Ⅴ) in Anhui yellow-brown soil and Xinjiang grey desert soil aged for 56 d were significantly higher than that aged for 7 d. The results show that: (1) Sb(Ⅲ) in Xinjiang grey desert soil was oxidized to Sb(Ⅴ) faster than that in Anhui yellow-brown soil. (2) Compared with 7 d of aging, the concentration of extracted Sb in Anhui yellow-brown soil and Xinjiang grey desert soil after 56 d of aging decreased by 9.3%-36.8% and 3.3%-47.0%, respectively. (3) The EC₅₀ (50% effect concentration) of exogenous Sb(Ⅲ) on the growth toxicity of C. elegans increased by 1.7 and 2.3 times, respectively; the EC₅₀ of exogenous Sb(Ⅲ) on the fertility toxicity of C. elegans increased by 1.1 and 2.4 times, respectively; and the EC₅₀ of exogenous Sb(Ⅲ) on the reproduction toxicity of C. elegans increased by 1.2 and 1.9 times, respectively. The aging process reduced the concentration of extracted Sb and the proportion of Sb(Ⅲ) with higher toxicity, resulting in the weakening of the toxicity of exogenous Sb(Ⅲ) to nematode. The effect of pH, organic matter content, and iron, manganese, and aluminum content on the oxidation of Sb(Ⅲ) and the adsorption of Sb led to the difference of aging effect and toxicity to nematode.