【Background】This study is to create a new environmental safety assessment technology of transgenic cotton in the"Twelfth Five"national project, which is aim at cultivating new variety of genetically modified organism． 【Method】Three experiment materials were put in trial， including two transgenic cottons with two Bt genes (cry1Ac, cry2Ab) and the double insect and herbicideresistant genes respectively， which were the observed species， and one nontransgenic cotton Ganmian No.11, which was the check test variety． The three materials were seeded on the earth′s surface and under the three centimeters depth of the earth on May 5, 2011 in order to compare their seeding emergence rate， plant height， reproductive process, the number of cotton boll opening valve， the floc valve dropping rate and survival competitiveness of the autogenetic seedling rate， evaluate their risk of weediness， discuss and verify the feasibility of this detection technology． 【Result】The differences of all above survival competitive ability between the double price of Bt gene (cry1Ac, cry2Ab) cotton， the double price of insect and herbicideresistant gene cotton and the control variety were less than 5% in general， which indicated the two transgenic cotton had no weediness risk． 【Conclusion and significance】It was not only feasible to use seeding on the earth′s surface as well as seeding under the three centimeters depth of the earth as detecting whether the survival competitive ability of new transgenic cotton has risk of weediness in the wasteland， but also had interactive reference effect on evaluation， which provided more reliable insurance on evaluation and had the significance of technique location．