Compared with the traditional network index, introducing the concept of "dependency" into the cotton trade network can reveal the characteristics of cotton trade more accurately. Based on the new trade dependence index, this paper constructs the 1999-2019 world cotton trade dependence network, analyzes the import and export trade dependence network of core trading countries in the past two decades, and uses temporal random index graph model to study. The results are as follows: (1) The countries with increased cotton import dependence are mainly distributed in Asia, and the network of export dependence is more concentrated than that of import dependence, and its network centers are mainly concentrated in Europe and America. (2) The rapid increase of China's cotton import dependence is reflected in the diversification of the dependent objects and the deepening of the dependence degree, and the sharp decline of export dependence is mainly due to the separation of low-dependent countries. (3) The formation of cotton trade dependence has the characteristics of ternary transmission, and the establishment of export dependence has the characteristics of "preference connection". A few countries with export dependence can further promote the formation of dependency through the dominant position established in the network. (4) Both the border relationship and the interactive nature of the free trade agreement between the two countries can significantly promote the formation of the cotton trade dependence relationship, but the economic level has a heterogeneous effect on the formation of the dependence relationship. Compared with low-income countries, middle-income countries are prone to import dependence, while high-income countries tend to form two-way import and export dependence. From the perspective of deepening international trade cooperation and optimizing the layout of the cotton industry, we can improve China's foreign dependence on cotton trade in the future.