There are various types of "Second Sound" in Pronunciation and Meaning of Er Ya. The paper finds that there are seven types of second sound: the second sound is for the pronunciation of the prefix with different sounds and the same meaning; the second sound is for the pronunciation of different text, and the first sound is for the pronunciation of the prefix; the second sound is for the pronunciation of the prefix with different sounds and meanings; the second sound is for the pronunciation of the prefix, and the first sound is for the pronunciation of different text; neither the second sound nor the first sound is for the pronunciation of the prefix; the second sound and the first sound have the same pronunciation; the second sound is read for the co-rhyme. The second sound not only reflects the phenomenon of mutational word-formation, but also reflects the modification of Jing Dian Shi Wen.