Earthquake emergency response is a complex process, and a large number of tasks are involved in the process of urban earthquake emergency response. To further study the collaborative relationship between organisations in the city-level emergency collaboration network driven by different emergency tasks, this study first constructs a task–organisation relationship framework and explores the collaborative mechanism of organisations driven by tasks. Then, the co-expression analysis was used to analyse the degree of correlation between task-driven emergency organisations. Finally, considering the influence of tasks on the degree of inter-organisational collaboration, this study constructs a task-driven weighted directed emergency organisation collaboration network. Social network analysis was used to reveal the structural attributes of the task-driven organisational collaboration network, the collaborative characteristics among organisations in the network, and the structural positions of organisations in the collaborative network. It is found that the task-driven earthquake emergency collaboration network was relatively loose, and there were small groups with close collaboration in the network. Most organisations in these small groups are in the same task module, and their tasks are similar. Commanders in the task execution process are usually at the core of the network, and these organisations are usually the main coordinators of the overall emergency collaboration and task module networks. These findings can improve our understanding of earthquake emergency organisational collaboration relationships and inspire the optimisation of urban earthquake emergency management.