1. A motion estimation method, applied to a video signal comprising a first frame and a second frame, the method comprising: capturing a matching window from the first frame; capturing a searching area from the second frame, the searching area comprising a plurality of searching blocks each having a size equal to that of the matching window; selecting a searching block from the plurality of searching blocks; calculating a difference between pixel data of the selected searching block and pixel data of the matching window to simultaneously obtain N total differences corresponding to N different searching blocks, N being an integer greater than 1; and determining a motion vector corresponding to the matching window according to at least the N total differences.