Abstract: Based on environmental protection automatic command system (C4ISRE)， the early warning technology for air nuclear pollution diffusion of the nuclear power plant was proposed. Firstly， an integration simulation environment of sea， land， sky and space for Hong Yanhe Nuclear Power Plant was constructed. Secondly， nuclear pollution diffusion scenario was set up and the HYSPLIT4.9 model was drove by meteorological data according to the scenario. Then， the atmospheric nuclear pollutant transport characteristics were simulated， and the early warning emergency response times for key areas were simulated and deduced. The deduction results showed that nuclear pollution air mass spreads into the waste storage tank factory building of conventional island after 71.885s， the airspace of heat engine repair shop and warehouse after 79.306s， the airspace of wastewater treatment plant and garage after 91.596s， the airspace of the boundary of the plant boundary and sea after 132.267s， plume boundary of emergency region 5km after 655.337s， the airspace of Wong Tung Village after 712s， plume boundary of emergency region 10km after 1240.535s， the airspace of Changxing Island town after 2527.945s， and plume boundary of emergency region 30km after 3468.65s.

Key words: C4ISRE, nuclear power plant, air nuclear pollution diffusion, integration of sea, land, space and sky, HYSPLIT