本文通过研究1853年艾约瑟《上海口语语法》一书的声调描写并结合上海地区方言相关现象,指出十九世纪中叶上海市区话存在两种声调的音变,一种是本地的阳上变阳平,另一种是来自权威方言的全浊阳上归阳去,两种音变层次叠加在一起,引起音变的双向扩散;加上这三个阳调类的调值十分接近,最终导致上海市区话阳平、阳上、阳去合并。 This essay, by studying the tone description of Joseph Yoseph’s Shanghai Oral Grammar in 1853 and the related phenomena in the dialects of Shanghai, points out that there are two tones of Shanghai dialect in the mid-nineteenth century, one is the local Yang Yang Ping, the other is from the dialect of the authoritative dialectical Yang go to Yang, two levels of sound superposition together, causing the two-way sounding diffusion; coupled with the tone of the three classes of tone is very close to the final Lead to the words of Shanghai Yangping, Yang, Yang to merge.