Changsha kiln was a famous export kiln during the Tang Dynasty. Products with the monochrome transparent lime glaze were fired in its early stage and later developed into those with the polychrome transparent or opaque lime glaze. At the time, Changsha kiln became famous and clearly reflected the cultural exchanges between China and foreign countries. The opaque glaze, especially the opaque white glaze, which was widely used in Changsha kiln, provided an important glaze layer for its color paintings. In view of this, we took some Changsha kiln porcelain pieces unearthed from Tongguan kiln and Huangsipu sites as the research samples and tested their bodies and glazes by means of energy dispersive X-ray fluorescence (EDXRF) spectrometry, optical microscopy (OM), scanning electron microscopy (SEM) and spectrophotometry. In our study, raw materials for the bodies and glazes, glaze opacification mechanism and reasons for the rise of opaque glaze products of Changsha kiln are discussed. These provide a scientific basis for the comprehensive understanding of the source of the glaze-making technology for Changsha kiln opaque glaze porcelains.