Aiming at the problems of unclear definition of engineering support task level and lack of comprehensive quantitative analysis of task decomposition, a capability-based engineering support task analysis method is proposed, the process of engineering support task decomposition is analyzed, a multi-level engineering support task system is constructed, and the definition and calculation formula of task granularity, correlation degree and task equilibrium degree are given. The feasibility and effectiveness of the task analysis method are verified by taking a barrier-breaking action as an example. It can provide support for commanders to accurately understand the intentions of their superiors and efficiently command engineering support actions.