Abstract: Transgenic Bt crops are commercial crops transformed with insecticidal genes which are derived from Bacillus thuringiensis, and they can produce a kind of insecticidal toxin to kill pests. With the wide application of commercialized transgenic Bt crops in large area, increasing attention has also been paid to the effect of released Bt toxin protein expressed in transgenic Bt crops on soil animals. Bt toxin protein may enter into soil ecosystem by several ways, such as root exudates, crop residues remaining in the field after harvest, and pollen spread during the flowering season. After entering into soil, Bt toxin protein may combine with the active particles in the soil. And the combined proteins are less likely to be degraded by soil organisms and soil enzyme. This combination leads to retention and enrichment of Bt toxin proteins and then may produce potential risk to non-target animals in the soil. The author systematically reviewed the latest research progress of the effects of Bt toxin proteins on soil animals, such as earthworm, nematode, etc, to provide reference for ecological risk assessments of transgenic Bt crops on soil ecosystem.