1. A virtual viewpoint synthesis method, comprising: establishing a left viewpoint virtual view and a right viewpoint virtual view and obtaining (u, v) to (u+1, v) pixel blocks for a pixel with a coordinate of (u, v) in a virtual viewpoint, that is, I(u)=[u, u+1); searching for a candidate pixel in a left viewpoint reference view using the left viewpoint virtual view, searching for a candidate pixel in a right viewpoint reference view using the right viewpoint virtual view, marking a pixel block in which a candidate pixel isn't found in the left viewpoint reference view and/or the right viewpoint reference view as a hole point; ranking the found candidate pixels according to depth, successively calculating a foreground coefficient and a background coefficient, and performing a weighted summation according to the foreground coefficient and the background coefficient, and, not including the pixels in the weighted summation if difference between depth value of current pixel and depth value of an initial pixel in the weighted summation exceeds a first predetermined threshold value; enlarging hole-point regions of the left viewpoint virtual view and/or the right viewpoint virtual view in the direction of background to remove a ghost pixel; performing viewpoint synthesis on the left viewpoint virtual view and the right viewpoint virtual view; and filling the hole-points of a composite image.