The present invention provides a method and device for color blood flow frame averaging. In the present invention, whether aliasing occurs to an output blood flow velocity of a previous frame is first determined. If aliasing does occur to the output blood flow velocity of the previous frame, the output blood flow velocity of the previous frame will be moved, and the moved output blood flow velocity of the previous frame is then subjected to the frame averaging. The present invention can improve and eliminate the “shadow” in the output blood flow velocity of the current frame due to velocity aliasing of the previous frame existing in the prior color frame averaging processing, such that the blood flow velocity appears more natural and has a more reasonable distribution.