【Background】Safety assessment of transgenic crop plants has been a concern, and only limited knowledge can be obtained from pre-release experiments. Once released, the survival and competitiveness of transgenic crops in non-cultivated land is one of the most important safety concerns. 【Method】We tested three transgenic cotton cultivars, two double-construct transgenic glyphosate- and insect-resistant cotton cultivars, and one non-transgenic cotton (CCRI 49), which was the isogenic control. Seeds were scattered on the soil surface, or planted 3 cm deep in late April and late May. We compared the growth parameters among the examined cotton varieties monthly from April to September, including survival rate, plant height, leaf number, stem diameter, sympodial branch number, bud and boll numbers, in order to test and evaluate their competitiveness on non-cultivated land and the risk of weediness. 【Result】Transgenic glyphosate- and insect-resistant cotton in wasteland was weak and stunted with slow and retarded growth. Only a few individuals sown in late April could produce a few small bolls; these were without mature seeds. Plants sown in late May were weaker, and no bud appeared until late September. 【Conclusion and significance】Transgenic glyphosate- and insect-resistant cotton had no competitive advantage and limited reproductive capacity on non-cultivated land, and consequently, low weediness potential.