This paper is mainly focus on the effect of the Zhuang group on the finals in the Yue-Dialects. I recommend the -i- losing in the Yue-dialects was caused by the retroflex sibilant of Zhuang group. By comparing the pronunciation of Zhuang group and jing, zhi, zhang group in the third division, we found out that they were different. zhuang group had a special sound feature, as their vowels were lower and backer. On the other hand, by using the comparative method to compare the written records and the modern Yue-dialects. This paper also tries to explain the changes of jing , zhi , zhuang , zhang groups. Modern Yue-Dialects have two types of sibilant consonant groups: Guangzhou type and Taishan type. But all the different were started by the development of 'jing≠zhi&zhang≠zhuang', they reflect the sound changes steps by steps.