Abstract: A text comparison method is adapted for comparing a query file with an existing file. The text comparison method includes: converting the existing file, by an irreversible method, to obtain a first intermediate file, wherein the first intermediate file includes a plurality of characters, and a number of different characters of the plurality of characters is a predetermined value; receiving a second intermediate file which is a file converted from the query file by the irreversible method; and according to a predetermined string length, comparing the second intermediate file with the first intermediate file by a high repeating-character comparison method to output a comparison result. Therefore, the second intermediate file can be created offline and then only the second intermediate file but not the original query file is submitted through interne for private text comparison.