The invention provides a method and a device for suppressing duplicate alarms. When an alarm is received, key words of the alarm are acquired; when the corresponding alarm is determined not to be recorded, the alarm is recorded with the acquired key words as an index, an initial liveness value is set for the alarm, and the alarm is reported and processed; when the corresponding alarm is determined to be recorded, the liveness value of the alarm is added through a preset activation function, and the alarm is discarded, wherein the preset activation function is an alarm time or alarm time function; when a fading period arrives, the liveness value of the alarm is reduced according to a preset liveness decay function, wherein the preset liveness decay function is the time for alarm times; and when the liveness value of the alarm is smaller than a first threshold, the recorded alarm is deleted. The scheme can effectively suppress reporting of duplicate alarms, and the device processing efficiency is improved.