The embodiment of the invention relates to an alarm method and an alarm device. The method is particularly as follows: obtaining first receiving power of a main unit and second receiving power of a spare unit, calculating the power difference between the first receiving power and the second receiving power, and when the power difference is a positive value and is not smaller than a first threshold value, alarming the spare unit and when the power difference is a negative value and is not greater than a second threshold value, alarming the main unit. Therefore, a unit needing to be alarmed in a network element is determined by utilizing the power comparing method and the unit is alarmed, so that the fault network element is checked and processed in advance, the timeliness is high, and the real-time is good.
