Ecosafety of transgenic cotton is reviewed in the paper with emphasis on its influence on soil ecosystem, including enrichment of transgenes in soil, effects of transgenes on soil biology, and horizontal transfer of transgenes in soil ecosystem. It is held that since so far not much research has been done on soil ecology of transgenic cotton, it is now hard to determine how much transgenic cottons would affect soil eco-environment. In addition, a brief introduction is given to the application of the Biolog-system and DNA-fingerprints technology to the research on soil ecological safety and safety evaluation of transgenic cotton.