In the face of global warming and the increasing pressure of international carbon emission reduction,the development of a low-carbon economy has become a common concern in all countries.The core of the development of a low-carbon economy is to improve the carbon productivity which can measure the economic benefits of carbon emissions per unit.Therefore,the identification of the factors of carbon productivity will provide an empirical evidence for increasing carbon productivity in various countries and exhibit a reference for reducing carbon emission intensity in China.Based on the 1996-2014 annual data of 36 countries,this study adopted a panel threshold model to study the threshold of merchandise exports structure for carbon productivity by using the economic development level and technology level threshold variables and learn how to use this influence to improve carbon productivity.The results demonstrate that the merchandise export structure has always been an inhibitory effect on carbon productivity,which is strong when the economic and technology development is in a relatively high level.We assume that merchandise export structure adjustment can improve carbon productivity when economic development and technology is in a proper level.In addition,the impact of merchandise export structure on carbon productivity has a significant regional difference.Based on the conclusion of this study,relevant suggestions are put forward.It is essential to optimize the structure of export commodities and improve energy efficiency from different perspectives of variable threshold system.It is also needed to solve the contradiction between carbon productivity increase and carbon emission increase,maintain appropriate economic growth rates,absorb advanced technology spillover,and improve the technical level.