In terms of the progress of the industry, the velocity and dynamic nature of the global environment, has caused serious damage and diminished our earth’s resources. A lot of effort has been spent on global sustainable development around the world, however, from a practical standpoint, the Incident or Hazard Command System (IHCS), especially emergency response for Debris-flow, is scare in Taiwan. The purpose of this study was twofold. First, it adopted the theory of task ontology to build up a three-level mediating representation for a task analysis, and the task of “emergency response for Debris-flow” served as an example. Second, from the modeling standpoint, a methodology, called TTIPP, was provided to systemically analyze the process of the task and subtask in terms of the inputs, outputs, mechanisms, and controls, using IDEF0 and Petri net.