This study uses the entropy weight method and coupling coordination model to explore the change law and temporal and spatial distribution characteristics of the coupling and coordinated development relationship of transportation, industry, and the environment in Guanzhong Plain urban agglomeration of China from 2008 to 2019. This study uses panel data of the transportation, industrial, and environmental systems of 11 central cities in Guanzhong Plain urban agglomeration and proposes a theoretical reference for further improving the high-quality development of Guanzhong Plain urban agglomeration. The results show that (1) the development evaluation indexes of transportation, industry, and environment subsystems of urban agglomeration are differentiated, the development growth rate of the transportation system is much higher than that of the other two systems, and the contradiction between industrial and environmental development and the transportation system is more prominent. (2) The spatial distribution of the comprehensive development index of the three systems has an obvious unipolar trend, and the difference in the development level between cities has intensified. Xi’an and Xianyang City exist as extremely hot cities, and the other cities are peripheral radiation cold spots. (3) The coupling and coordinated development level of urban agglomeration tends to be optimized and improved overall, but tending toward imbalance. Among them, Xi’an City has been in a unipolar situation of high coupling and coordination, but the gap between the cities in coupling and coordination has gradually narrowed, and the number of cities with coupling and coordination has gradually increased, tending to be concentrated and distributed. Therefore, to realize the high-quality development of Guanzhong Plain urban agglomeration, it is necessary to first actively build a spatial development pattern of “one circle, one axis, and three belts,” promote the construction of a high-speed railway, build a rapid transportation network, and change the current development characteristics of traffic lag. Second, it is necessary to strengthen the radiation driving role of central cities and gradually reduce the differences in the coupling and coordinated development level of regional transportation, industry, and environment. This study plugs the gap in existing research on Guanzhong Plain urban agglomeration, a national urban agglomeration under the new orientation of reform and opening up, and places transportation, industry, and environment in the same system, breaking through the research on the one-way relationship between each two systems.