1. A method for processing border of a computer figure to be merged into a background image, comprising: performing a border searching process for obtaining information including image coordinate values and image pixel values of a border of the computer figure displayed on a computer display; obtaining information of pixels of the background image corresponding to a border image range of the computer figure when the computer figure is going to be merged to the background image; responsive to the pixel information of the border image range of the background image, applying a border effect with different effect weights to the background pixels of the border at different positions, so as to create a new computer figure with the border effect to be merged to the background image; wherein the border effect is a pictorial effect of convex lens or concave lens applied to all or part of the border of the computer figure, and a plurality of different mask weights are set to the background image corresponding to the border of the computer figure according to a distance relationship; wherein the steps of obtaining information relating to the border of the computer figure, obtaining the pixel information of the background image corresponding to the border of the computer figure, and applying the border effect are continuously performed when a position of the computer figure is changed, a size of the computer figure is resized, and/or an angle of the computer figure is rotated.