Pot culture experiment on the effects of 1,2,4-trichlorobenzene (TCB) stress on active oxygen metabolism of germinated soybean seeds indicated that during the beginning (1st-3rd day) of 100-300 micrograms.g-1 TCB treatment, the respiratory peak appeared earlier, and the respiratory rate, the accumulation of superoxide radical (O2-.) and H2O2, as well as the malondialdehyde (MDA) content were all enhanced. During 1-6 days of TCB stress, peroxidase (POD) activity gradually increased, and superoxide dismutase (SOD) activity increased firstly, and decreased afterward. These results suggested that the injury effects of TCB stress on germinated soybean seeds were achieved by excessive accumulation of active oxygen resulted from the degradation of active oxygen scavenging enzyme system.