The invention relates to the technical field of wireless sensor network simulators and discloses a large wireless sensor network simulator which is established by adopting a layered architecture and a method for establishing the wireless sensor network simulator. The whole structure of the wireless sensor network simulator is remarkably hierarchical so that the wireless sensor network simulator has better expandability and modifiability; and events and nodes in the simulator are realized and managed by an effective data structure so that a large sensor network simulation experiment can be supported and a high execution speed can be achieved.