A method for identifying state of macro block of de-interlacing computing and an image processing apparatus are provided, the method is as follows. A video frame is divided into a plurality of regions, where each of the regions includes a plurality of macro blocks. Then, a basic threshold corresponding to each of the regions is provided according to a position of each of the regions in the video frame, and a first macro block is identified to be a first type macro block or a second type macro block according to the basic threshold corresponding to one of the regions where the first macro block of the macro blocks locates. Then, a corresponding de-interlacing computing step is performed on the first macro block according to an result that the first macro block is identified as the first type macro block or the second type macro block.