A method and apparatus for video encoding or decoding used by an AVS2 (Second Generation of Audio Video Coding Standard) video encoder or decoder respectively are disclosed. According to this method, first motion vectors associated with spatial neighboring blocks of a current block are determined. For each spatial neighboring block, a value of 1 is assigned to a first BlockDistance associated with the spatial neighboring block if a corresponding first reference picture is a G picture or GB picture. Motion vector predictor candidates are derived from the first motion vectors by scaling each first motion vector according to a corresponding first BlockDistance and a current BlockDistance. A final motion vector predictor is determined among the motion vector predictor candidates. The current motion vector is encoded or decoded using the final motion vector predictor