A Precious Canon of the Jade Candle (Yuzhu baodian),an encyclopedia of local customs compiled by Du Taiqing (6^(th) c.),contains material from the pronunciation glossing system created by Du himself. This material, however, has long remained unheeded in relevant scholarship. In fact, an analysis will yield hints to reconstruct some characteristics of Du's phonetic system. These characteristics may be compared with the phonetic system of the Qieyun, which represents the literary language system of the sixth century, to show the similarities and differences between them. With these findings, one may see the phonetic differences of dialects in Du's time.