王弼為體用範疇之首唱者，然其體用原義是否如後世習用的「本體、現象」，學界漸有不同看法。本文首先透過對王弼體用舊說之省察，檢視各家說法之困難。其次，藉由對王弼文獻的回顧，指出王弼之體用思想實得於《易經》的啟發，而自覺且嫻熟地運用於《老子注》與《周易注》中。要言之，王弼之「體」為道德特性，「用」則為相應於該道德特性的行為特性。就「道」及「與道同體」的聖人而言，乃是以無為體、以無為用，故能得無所偏為之功；就失道者而言，乃是以有為體、以有為用，其功則或為仁義禮節，或為裂發歇竭滅蹶。對王弼而言，體用既是對道與失道者之存在特性的說明，亦是工夫進路的提點。是以，將王弼之體用理解為後世「本體／現象、功用」習義，並將之與無有、一多、本末、母子等視為對應範疇，蓋未盡實。

Wang Bi is the initiator for the category of tiyong. Wang Bi's original meaning of tiyong is ”substance and function” or not, the scholars have different viewpoints gradually. This article examines the philosophic difficulties of various interpretations of Wang Bi's tiyong in the past. By reviewing the text of Wang Bi's, this paper points out that Wang Bi's thought of tiyong was inspired by Zhouyi, and Wang Bi made use of the category of tiyong to the commentary on Lauzi and Zhouyi self-consciously and expertly. In one word, Wang Bi's ti is the internal characteristic, yong is the behavior characteristic which corresponds to the internal characteristic. For dau and the saint whose internal characteristic is as same as dau, they take non-being as internal characteristic (yi wu wei ti 以無為體) and take nonbeing as behavior characteristic (yi wu wei yong 以無為用), so that thay can accomplish all achievements. But for people who deviate from dau, they take being as internal characteristic (yi yo wei ti以有為體) and take being as behavior characteristic (yi yo wei yong以有為用), so they can accomplish some achievements only, even thay always cause disasters. Wang Bi used the category of tiyong to explain the different levels and characteristics between the saint and people who deviate from dau, and he presented a progressive direction: take non-being as internal characteristic and take non-being as behavior characteristic.