Abstract: [Objective] In order to provide the effective control of Agrotis segetum in Tajikistan, the occurrence and population dynamics of A.segetum in Xinjiang and Tajikistan were compared and the potential reasons were discussed for the population succession and declination in Xinjiang, China.[Method]A.segetum moths were monitored by light traps in Shihezi (from 1980-2011) and Tajikistan (2014).The occurrence and population variation were analyzed according to the monitoring data.[Result]In Tajikistan, A.segetum developed 3-4 generations in a year and could be caught up to 90 individuals per light per night at the peak time.In most places of Xinjiang, A.segetum developed 3 generations yearly, in some parts of southern Xinjiang, it could develop 3-4 generations and while in few areas of northern Xinjiang it could develop 1-2 generations.At the peak timing, A.segetum could be caught less than 40 individuals per light per night, which indicated that A.segetum, were no longer the major insect pests in Xinjiang.[Conclusion]A.segetum can develop 1-2 generations more in Tajikstan than in Xinjiang.A.segetum can develop 3-4 generations per year in Tajikistan, while 3 generations yearly in most places of Xinjiang.A.segetum trapping moths in Tajikistan are far more than in Xinjiang region of China at the fastigium.