[Aim] The Yangtze River Basin and the Yellow River Basin have decreased sharply leading to cultivation of cotton on coastal saline or dry lands. The objective of this research was to compare the impacts of transgenic versus non-transgenic cotton cultivation on pest insect populations and the efficiency of pesticides for pest control.[Method] The paper surveyed and analyzed the insect population dynamics in transgenic cotton fields in Dongying in Shandong Province, and Zaoqiang in Hebei Province, which were sprayed or not with pesticides in 2013 and 2014.[Result] The transgenic cotton in saline alkaline and dry soil had better control effect on target pests than non-transgenic cotton. The populations of non-target pests such as Aphis gossypii, Bemisia tabaci and Miridae, and predators, such as Propylaea japonica and Erigonidium graminicolum, were not significantly different between the two types of cotton fields. The Chrysopa population was smaller in transgenic cotton fields than non-transgenic cotton fields. Chemical pesticides effectively controlled Helicoverpa armigera eggs, larvae of cotton bollworm and cotton aphids. The control of Bemisia tabaci and fleahopper differed among fields and yearly, with greater effects observed for Propylaea japonica.[Conclusion] The effects of saline alkali drought land on different pests and natural enemies in cotton fields were different, and compared with the non-Bt cotton, the insect community structure of transgenic cotton fields in saline and dry land showed no difference.