Karlgren's monumental work "Etudes sur la phonologie chinoise" (1915~26) has no doubt exerted great influence on Chinese phonology and dialectology. He reconstructed the sound values of Middle Chinese on the basis of 33 Chinese dialects, Sino-Japanese, Sino-Korean, and Sino-Viet-names. However, before Karlgren, a similar effort had already been made by a Japanese scholar, Ogawa Naoyoshi, as early as 1907. He conducted broad research comparing the sounds of Chinese dialects and Sinoxenic characters by means of modern linguistics. He reconstructed the phonetic values of Middle Chinese initials and final consonants and, in some respects, achieved more reasonable results. This was highly significant in the history of Chinese linguistics. This paper has two main goals. One is to compare the studies on Chinese phonology made by Karlgren and Ogawa, particularly on phonetics, historical linguistics, and phonological comparison; the other is to explain why Ogawa has been ignored, in spite of his achievements in the field of Chinese linguistics. In terms of research methodology, we regard Karlgren as superior to Ogawa in the reconstruction of the phonetic values of Middle Chinese, as well as in the investigation and description of Chinese dialects. However, in terms of research results, there are some respects in which Ogawa is superior to Karlagren. The most important thing is that Ogawa was the first scholar to study Chinese using modern linguistic methods, and therefore his position as a pioneer in the history of modern Chinese linguistics deserves to be recognized.