It is important and difficult to identify the Hazard before a disaster happen because disaster often happens suddenly. This paper proposes a new method – State Transition Graph, which based on visual data space reconstruction, to identify hazard. The change process of the system state movement from one state to another in a certain period is described by some state transition graphs. The system state, which is safe or hazard, could be distinguished by its state transition graphs. This paper conducted experiments on single-dimension and multi-dimension benchmark data to prove the new method is effectiveness. Especially the result of stimulation experiments, based on the Yangtze River tunnel engineering data, showed that state transition graph identifies hazard easily and has better performances than other method. The State transition graph method is worth further researching.