The theory of Duqu as broadly defined includes the theory of prosodic rule and the theory of performance. The playwright composes by the sounds in order to make the performers chant smoothly and thereby meet the aesthetic demands of sounding effect. Hence, the meaning and purpose of composing and examining Chinese traditional opera by prosodic rule is not only to pursue the precision of prosody of language in literature, but also to accomplish the harmony of melody in performance. "Prosody" then is the common element between the precise language prosody and the harmonious melody. It is also the merging of the theories of prosodic rule and performance. The close relation between prosody and Duqu is derived from the char-acteristic of the tones of Chinese language. From the view of prosody in Chinese traditional opera to select related materials, this essay takes Zhongyuan yinyun as the main material to explore the close relation between composing by sound and smooth singing. The principal content in Zhou Deqing's prosody in northern sanqu and zaju is that "sounds are separated into ping and zhe," and "language is parted into yin and yang." "Sound" and "language" are synonymous and both mean tones of sounds or tones of language. The objective to place the knowledge of prosody in the creative theory of traditional Chinese opera is to provide composers with creative works, to achieve the unity of "embellishment of language and the perfection of prosodic rules." The resulting effect is the fulfill-ment of the esthetic principle: "singing the words must be sounding the words". This essay argues that the incorporation of prosody into the formation of the theory of Duqu in northern sanqu and zaju was initiated Zhou Deqing. Furthermore Ehou had also produced some fine sholarly work on the fusion of the prosody in northern sanqu and zaju and Chinese traditional opera.