The insecticidal crystal protein gene of Bt (Bacillus thuringiensis) has been the most extensively used one in plant insectresistant genetic engineering.Along with commercialization of large groups of Bt-transgenic crops, the impact of Bt toxins released from transgenic plants on the soil ecosystem has aroused high concerns.In this paper the environmental behavior and biological effects of the Bt toxin are reviewed, addressing ways of Bt toxins released into the soil from transgenic plants, its movement, bond onto soil surface-active particle, degradation, persistence and effects on organisms and enzymes in the soil.