The problem of closed labials in Old Mandarin, the author's another article published in 1994, demonstrated the existing of the closed medial u in the labials of the four rhymes in Zhongyuan Yinyun (中原音韻), i.e. qiwei (齊微), zhenwen (真文), gege (歌戈) and huanhuan (桓歡), although these labials have no open medial contrasting with it. The proof mainly came from the works such as Menggu Ziyun (蒙古字韻), Gujin Yunhui Juyao (古今韻會舉要), Sisheng Tongjie (四聲通解) and some modern Chinese dialects. This articles continues the proving further, provides the data found in some Rhyme tables in the dynasties of Ming and Qing, and also discusses some phonological issues related to the problem.