The poems of Li Bo and Du Fu are similar in their startling spirit, but contrast in styles with playful lightness versus condensed heaviness. Such a way of juxtaposition originated from Yan Yu’s Canglang’s Remarks on Poetry. Throughout history, whether the poetics of Yan Yu is based on the stillness of Zen or the activeness of High Tang’s spirit has caused considerable controversy. How is the dimension of stillness possible in terms of Li Bo’s style of playful lightness? To deliberate this question, we start with examining the discussion of stillness at the word and sentence levels in a fake version of Yan Yu’s commentary on the poems of Li Bo. With reference to the elements of brightness, coolness, dryness and weightlessness, we investigate how Li Bo nourished his own style from tradition on one hand, and developed a contrasting style from that of Du Fu on the other. The major conclusions of the present essay include: (1) Holding a high opinion on the poems of High Tang, Yan Yu highlighted the Li-Du juxtaposition. In the course of his commenting, more has been on activeness than on stillness. When he discussed the poems from the Zen perspective, nonetheless, the still spirit of Zen was involved. The emergence of the fake version of Yan Yu’s commentary has its inner logic. (2) The analysis at the word and sentence levels showed that Li Bo’s style actually incorporated a dimension of stillness. This dimension was often made possible by the repeated use of related words in a certain category, mobilizing multiple senses to achieve the effects of brightness, coolness, dryness and weightlessness. (3) In the process of inheriting the tradition since the Six Dynasties, Li Bo had also fully exercised his own choices and further developed them remarkably. (4) With respect to the angle of Li-Du juxtaposition, the elements of brightness, coolness, dryness and weightlessness that characterize the style of playful lightness are imbued with special meaning.