1. A computer-implemented method for adjusting characters of a page using an electronic device being executed by a processor of the electronic device, the method comprising: determining a selected page on a display device of the electronic device; acquiring sizes of characters on the selected page; computing an adjustment ratio of the characters on the selected page according to a predetermined calculation method; adjusting a size of each of the characters on the selected page according to the acquired sizes of the characters on the selected page and the computed adjustment ratio of the characters on the selected page; and displaying each of the characters on the selected page on the displaying device with the adjusted size of each of the characters on the selected page.