The present study investigated sets of spoken and written data from different corpora to understand the directionality of grammatical change of do-constructions in Taiwan Mandarin. The variation takes place in two different ways: The ‘modifying-v variant’ modifies the head noun dòngzuò ‘action’ in a VP starting with zuò ‘do’; the ‘nominalized-v variant’ is the head of the direct object. The nominalized-v variant with modification occurs when language users engage in reportages to increase informational content, whether oral or written. The modifying-v variant with modification occurs in written reportages to deliver more information. In speech, however, the modifying-v do-constructions mostly lack modification, forming an individualistic linguistic style. The findings demonstrate that written language has affected spoken language, the same variant could develop distinct structural patterns to meet different communicative needs, and some structural development of the two variants could converge, break the conventional distinction between speech and writing and reveal language specificity.