To analyze the synergistic relationship among urban emergency organizations during institutional reforms, 24 natural disaster-specific emergency plans from Xi'an city were used as the data sample. Social network analysis was employed to examine the coordination and collaboration between departments involved in emergency response, mitigation, and rescue during natural disasters. From a temporal perspective, the dynamic changes in the network structure were explored, and the characteristics of indicators such as density, centralization, and average distance were assessed. Using a "coherence and constraint" two-dimensional framework, institutional roles were classified and analyzed from three dimensions: institutional characteristics, functional positioning, and organizational structure. The CONCOR(Convergence of Iterated Correlation) algorithm and E-I index method were applied to depict the internal logic of network governance structures and the evolution of organizational relationships. The results show that the concentration of the emergency organization collaborative network increased from 0.577 6 to 0.723 5 after the institutional reform, indicating that the network structure shifts from a decentralized network with loose collaboration among multiple entities to a tightly-knit network centered around the Xi'an Bureau of Emergency Management. The highest core degree of institutions increases from 0.342 to 0.369, while the lowest constraint degree decreases from 0.166 to 0.087, reflecting a trend toward the unification of command responsibilities. The network organization follows a core-periphery governance structure, with the boundaries between core and peripheral organizations becoming increasingly clear and reinforced.