Urban networks have been widely examined using infrastructure connection and firm connection data. In particular, urban networks constructed based on firm connection data have been used to depict the circulation of capital, information, personnel, and products between cities. Existing studies on firm connection networks rely on either inter- or intra-firm relationships. However, there exist various important extra-firm relationships, such as those between firms and governments, research institutions, and non-profit organizations. This study innovatively incorporates the extra-firm relationships between governments and firms into urban network construction to provide new insights into urban network research. Based on the transaction data of Chinese government procurement activities in 2018, this study provides an in-depth analysis of spatial connection pattern and structure characteristics of supply-demand network in Northeast China by using the methods of GIS and Social Network Analysis, and thoroughly discusses the influencing factors on this basis. The results of the study are as follows: 1) The spatial connection structure presents a connection pattern with Changchun as the radiation center and the Harbin-Dalian Corridor as the main axis in the network for central projects. While network for local projects mainly show the characteristics of intra-provincial connections with the 3 capital cities of Harbin, Changchun and Shenyang as divergence centers, and the scope of government and firm activities between cities is relatively limited in network for local projects. At the same time, the number of participating cities and linkages between the supply-demand network for local projects and central projects is obviously different, and the coverage of local project network is wider. 2) No matter network for central or local projects, the 3 capital cities of the Northeast China are in the absolute center of the local supply-demand network. The degree centrality of Harbin, Changchun, and Shenyang is much greater than that of other cities in the region, and the net outdegree is always positive. With multiple cohesive subgroups, there are many small groups in the networks of Northeast China. 3) Affected by the type of budget, there are obvious differences in the structure of urban network for central and local projects; At the same time, the economic strength of a city could affect the position of a city in the network by indirectly influencing the economic activities of its agents in the network, that is, the stronger the city’s strength is, the greater the centrality is in the network; However, in actual procurement activities, the behavior of government and firms will be restricted by geographical distance and administrative boundary; Finally, since government procurement activities are one of the government’s macro-control measures, some national policies can directly affect the strength of government-firm linkages, and thus effectively guide the coordinated development of urban supply-demand networks.
