Through air defense exercises, we can clearly distinguish the significance of air defense warning signals. In the event of a war or a major disaster, ordinary people can get information from air defense early warning signals to reduce casualties and losses. Air defense warning can be divided into early warning, air raid warning and disarming warning. Early warning: sound for 36 seconds, stop for 24 seconds, repeat for 3 times as a cycle, and the time is 3 minutes. Citizens immediately stop all "work", turn off the power supply at home, turn off the gas, put out the fire, close the doors and windows, carry valid documents, daily necessities and protective equipment, and quickly evacuate to nearby underground air defense bunkers, civil air defense projects and air-raid shelters. Air raid alarm: sound for 6 seconds, stop for 6 seconds, repeat 15 times as a cycle, and the time is 3 minutes. Unable to enter underground air defense bunkers, civil air defense projects, and air-raid shelters, citizens used the terrain and landforms to escape nearby, kneeling on the ground with their hands on their heads. Disarm the alarm: After a long sound for 3 minutes, citizens can get out of underground air defense bunkers, civil air defense projects and air defense shelters and return to normal "work".