Abstract: Effects of Pb(NO₃)_2on activities of three antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the earthworm, Eisenia fetida, were investigated with both freshly spiked and aged soils. The results showed that Pb(NO₃)₂ caused a significant effect on activities of three antioxidative enzymes at 200-1000mg/kg. When toxicity tests were carried with freshly spiked soils, the SOD and CAT activities decreased with the exposed dose of Pb(NO₃)_2in creased at the 1st, the 14th, the 21st day and the inhibition rates were about 40% with the treatments with high concentrations. The POD activity was basically not affected except for the 1st and the 3rd day. When toxicity tests were carried with aged soils, the SOD, POD and CAT activities increased with exposed dose of Pb(NO₃)_2increased in the first day, and the simulation rates at higher concentrations were 359%, 147% and 233%, respectively. However, the three enzymes significantly decreased at the 3rd, the 7th, the 14th and the 21st day. In addition, the activity trend of SOD was generally in accord with that of the activity of CAT for both freshly spiked and aged soils. All these indicated that the soil aging leads to effects on the toxicity of Pb(NO₃)₂ and it should be taken into consideration when toxicity tests of Pb(NO₃)_2were carried out.