In traditional Chinese music, the determination of mode and key for pieces within the pentatonic system involves three analytical levels: gong (the keynote system, comprising the pitch level of the keynote and the scale), jun (a specific heptatonic scale), and diao (mode). Determining the pitch level of the keynote relies on identifying the five fundamental tones. The first step is to check for the presence of any non-pentatonic tones, which are structurally auxiliary in nature. If such tones are present, the principle of auxiliary-tone deviation is applied; if not, the fundamental and non-pentatonic tones can be distinguished directly according to the pentatonic framework. Subsequently, the principle of the gong-jue major third (the interval between the keynote and its mediant) can be used to determine the keynote more straight forwardly and efficiently. If this major third is absent among the five fundamental tones, the principle that the keynote must be present is employed to identify the form containing it. In pentatonic music, changes of the keynote can be categorized into three types based on the clarity of the new keynote: foreign-key coloration, temporary key-shift, and full key-shift. Scale analysis is an essential part of modal-key analysis and requires greater emphasis. Whether an analysis of jun is needed depends on whether the modal-key structure of the piece contains elements related to it. Once the keynote and scale are clarified, the mode can be determined by examining the hierarchical relationships among the tones.