A method for bitstream editing is provided. The method includes steps of: fetching a first original image from a source multimedia bitstream; performing variation processing on the first original image to generate a plurality of transformed pictures; performing keypoint extraction according to comparison results of the transformed pictures to obtain a plurality of candidate pixels; locating a first advertisement bitstream from an advertisement bitstream database according to the plurality of candidate pixels; and inserting the first advertisement bitstream to the source multimedia bitstream.