In order to explore the coupling and coordinated development degree among the three subsystems of carrying capacity of resources and environment, economic development and new urbanization in Northwest China, taking the five provinces and regions in Northwest China from 2005 to 2019 as the research object, an evaluation index system is established from the three dimensions of carrying capacity of resources and environment, economic development and new urbanization. The coupling and coordination relationship and action mechanism among the three subsystems and the temporal and spatial characteristics of system coupling and coordination degree in five provinces and regions are studied by using the coupling coordination degree model and the obstacle degree model, and the relevant influencing factors are further analyzed. The research results show that the comprehensive evaluation index of the coupling coordination of carrying capacity of resources and environment, economic development and new urbanization development in Northwest China has an upward trend during the research period, and it is generally changing to a better state. The increase of the comprehensive evaluation index of economic development subsystem and new urbanization development subsystem during the research period is significantly greater than that of carrying capacity subsystem of resources and environment, and their system coupling degree is at a high level. The degree of coupling and coordination shows a steadily upward trend, and the type of coupling and coordination has completed the transformation from near imbalance to intermediate coupling. In the future, the concept of sustainable development should be established, the level of carrying capacity of resources and environmental should be improved, and the mode of economic development should be changed so as to promote the coordinated development of the three subsystems in Northwest China.