An empirical study on R&D welfare effects of genetically modified cotton from 1996 to 2008 was carried out by using agricultural R&D economic surplus model under the open condition.The results showed that,firstly,agricultural treadmill effect triggered by technological progress is harmful to cotton farmers’ welfare,and including China’s cotton planter,cotton producers in every country suffer notable loss on economic benefits by growing genetically modified cotton; secondly,cotton consumers are the biggest gainers of this new technology,and with the rising of adoption rate of genetically modified cotton,consumer surplus will have much more increase,while the researchers will get considerable technology fees because of intellectual property rights protection; thirdly,for a country as a whole,the developing countries such as China and India are the biggest winners of this new technology.