1. A sorting method of data documents, adapted to an electronic device, and the sorting method comprises: retrieving a plurality of keywords from contents of a plurality of data documents; retrieving keyword rankings corresponding to the plurality of keywords by a search engine; searching keyword categories corresponding to the plurality of keywords; and generating a sort algorithm based on the plurality of keywords, the keyword ranking and the keyword category of each of the plurality of keywords, and a current ranking of each of the plurality of data documents, wherein the sort algorithm is used to calculate a predicting ranking of another data document and to sort the another data document.