A semantic processing method includes the following steps of: segmenting an input sentence into a plurality of lexicons according to a lexicon database, wherein the lexicon table includes a plurality of table blocks, and the table blocks are respectively located at a plurality of levels of the lexicon table; referring one part of speech or a plurality of parts of speech, corresponding to one of the lexicons of the table blocks, in the lexicon database; performing at least one grammar rule for each of the table blocks of the levels according to the part of speech, the plurality of parts of speech, the part of speech sequence or the plurality of part of speech sequences corresponding to the table blocks of the lexicon table; and outputting a parse tree according to the table blocks in the lexicon table that conform to the at least one grammar rule.