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; wherein the adjustment ratio of the characters on the selected page is computed according to the predetermined calculation method by: acquiring sizes of characters in a first preset region of the selected page; acquiring sizes of characters in a second preset region of the selected page; computing a weighted average size according to the sizes of the characters in the first preset region and the sizes of the characters in the second preset region; and computing the adjustment ratio of the characters on the selected page by dividing a preset size by the weighted average size; wherein the weighted average size is computed according to a formula of 
 Fw avg=Σ i=1 n ( f ( i )/ n×w 1)+Σ i=1 m ( g ( i )/ m×w 2))/( w 1+ w 2), f(i) representing a size of a ith character in the first preset region, w1 representing a weight corresponding to the characters in the first preset region, n representing a number of the characters in the first preset region, g(i) representing a size of a ith character in the second preset region, w2 representing a weight corresponding to the characters in the second preset region, m representing a number of the characters in the second preset region.