The embodiment of the invention provides a method, a device and a system for cancelling echo out. The method for cancelling the echo out comprises the following steps: receiving a sound signal sent by a far-end meeting place and azimuth information which corresponds to the sound signal; according to the azimuth information, judging the playing region in the far-end meeting place, to which the sound signal belongs; performing double-talking state detection on the sound signal; if the sound signal is in the single-talking state, upgrading the virtual filter factors of an echo path which corresponds to the playing region to which the sound signal belongs; and performing echo cancelling out by utilizing the virtual filter factors. When the echo cancelling out is performed by the embodiment of the invention, only the virtual filter factors of the echo path which corresponds to the playing region to which the sound signal belongs need to be upgraded, i.e., only the virtual filter factors of which the number is the same as that of microphone arrays need to be upgraded at most at the same time, therefore, the operation complication when the echo cancelling out is performed is greatly reduced, thereby, the requirement on the processor performance in the echo cancelling out process is reduced, and the hardware cost is reduced.