This paper first introduces the main negatives of Tangxi dialect in Wu dialects. Based on this, it compares the negatives of Tangxi dialect with those of some dialects in Mandarin, Wu, Hui, Xiang dialects as well as Pinghua from phonetic, morphemic, and semantic angles. Finally, it discusses the origins and functions of sentence-final negatives. Some conclusions made in the paper follow as: phonetic reduction is one means of grammaticalization of negatives; negative concepts of bu (_??_), wei (_??_), wu (_??_) fall into three categories: trichotomy, diachotomy, and monochotomy in Chinese dialects; it is common that negative verb wu (_??_) extends to negative adverb wei (_??_) in Chinese dialects; sentence-final negatives usually result from positive-negative questions' omitting constituents after negatives; sentence-final negatives tend to change into interrogative modal particles.