A method and a system for obtaining motion vectors and boundary strengths of an image are disclosed. The method comprises the steps of: S202, determining motion vector prediction direction information and motion vector calculation method information of a block to be decoded currently according to a type of the block to be decoded currently and a type of a macroblock/sub-macroblock in which the block to be decoded currently is located; S204, obtaining related information needed to calculate a motion vector of the block to be decoded currently using the motion vector prediction direction information according to the motion vector calculation method information; and S206, calculating the motion vector of the block to be decoded currently using the related information obtained, and calculating a boundary strength of the block to be decoded currently using the motion vector of the block to be decoded currently.