In Kunqu's most refined form, a performance is accompanied only by a single flute and perhaps a drum. This sort of performance could be heard at literary gatherings in the homes of the wealthy. More popular performances include more instruments, but always instruments in a high register. The traditional notation itself does not specify the instrumentation. It contains only one line of music and the instruments(s) and singer(s) would perform largely in unison.

Chinese is a monosyllabic tonal language. The word melody is created by the tone. The combinations of tones make up for the music of Chinese language. In Kunqu, poetry is written to fit a large number of fixed tone patterns. Melodies are then developed from those tone patterns without interfering with word melody, so every word in the poem can be sung out properly. Each tone pattern melody has two essential elements. One is reference note and the other is key note. The reference note, usually the last note of the key melody of the tone pattern, is used to determine the mode of the melody. It has twelve tones. The key note is used to determine the pitch of the melody. It has seven tones. Combining of these two elements, it defines the characteristics of the tone pattern melody. In theory, there are eighty-four different melody types. After merging and elimination, the most frequently used melody types are only thirteen.

The music in one play is usually from slow to fast. There are six beat types in Kunqu music: 4/4 beat, 2/4 beat, 1/4 beat, free beat, extended 4/4 beat and extended 2/4 beat. The extended 4/4 beat is like an 8/4 beat to make the music more gentle, ethereal and relaxed. The extended 2/4 beat is similar to a regular 4/4 beat, but the rhythm is stronger. The rhythm of free beat is based on the singer's interpretation of the poetry.

Prior to Kunqu the best known opera forms were the northern Zaju and southern Nanxi. Northern opera was considered to be vigorous, bold and stirring, the music more rhythmic, staccato and sometimes diatonic (7-tone scale); it was more syllabic, emphasizing the text. Southern opera by contrast was said to be more gentle, ethereal and relaxed, the music more free, slower and pentatonic (5-tone scale); it was more melismatic, emphasizing the music. Kunqu was codified and standardized in the mid-16th century by several musicians and literati in the Kunshan region, near Suzhou. It was based on the local music and drama, with major outside influence coming from the regional operas of Hangzhou and another popular southern music called Yiyangqiang. Kunqu is a southern style opera with the northern style of singing incorporated. One play may consist both southern style and northern style tone patterns to emphasize the contrast between two roles.

Sometimes background music can be used to enrich the performance. In traditional, set tone pattern melody without poetry is used for set condition. In this arrangement, the background music is integrated into the play with similar characteristics of the poetry and singing.