In the Lun-yin-li section of the Shiji-zhengyi, Zhang Shoujie enumerated 33 pairs of Chinese characters whose pronunciation made binary phonetic opposition Qing (clear) vs. Zhuo (muddy). The present author makes a critical text of Lun-yin-li, and observes that the first 11 pairs are pertaining to some specific characters which had different readings according to their meanings, while the following 22 pairs concerned the distinction of the underlying phonemes. The phonemic distinctions underlying the 22 pairs cover both initials and finals, the latter especially concern the distinction between the rime Zhi (to go) and the rime Zhi (grease). Zhang Shoujie states that these Qing-zhuo distinctions are very liable to be confused, and requires the scholars to keep them strictly. From his statements we can know that, at the first half of the 8^th century, the subtle phonemic distinctions in the Qieyun system as the norm of reading pronunciation were not easy to be maintained. It would be noted that the Qing-zhuo confusions stated by Zhang all concern the defects of the southern people at that time.As an addendum, the author refers to the view by Tadashi Ueda that the term Qing- Zhuo in the Qieyun Wang-Er fragment might express voiceless vs. voiced opposition of the initial consonants, which was not equal to the meaning in Lun-yin-li.