It is common knowledge that Chinese characters have three elements of form, sound and meaning. In the past, Korea has imported and utilized these Chinese characters since ancient times. However, the way the Chinese pronounce these words and the Koreans pronounce these characters are drastically different due to the different phonological system that exist between the two countries. It has been actually been proven that the traditional Korean reading sounds of the Chinese characters derive from the Chinese traditional pronunciation guide dictionary, the Yunshu(韻書). The “Jeon-un okpyun(『全韻玉篇』)” which is a Sino-Korean dictionary actually covers about 620 Chinese characters with attachments of both the correct sounds and popular reading sounds. What is interesting is that when the most common reading sounds recorded in this dictionary were compared with the ones in yunshu, they could not be found in the Fanqie(反切: Traditional Chinese lexicography) of the yunshu. Therefore, based on some of the findings including the above fact, it may be possible to draw a conclusion that the popular reading sounds in the “Jeon-un okpyun“ are sounds which have been created by the Koreans themselves.