Yue kiln celadon is the earliest celadon manufactured with a precise fire system in China, and the use of porcelain saggers to firing Mi’se celadon is the unique firing technique of the Yue kiln. In order to reveal the processing feature of porcelain sagger and its influence on celadon of Tang and Five Dynasties, saggers, which were unearthed at the Housi’ao kiln site in the Shanglin Lake of the Yue Kiln, were characterized via a variety of testing methods. In this paper, energy dispersive X-ray fluorescence spectrometer (ED-XRF), super depth of field microscope, scanning electron microscope (SEM) and other mondern test methods, were applied on the porcelain sagger, common sagger, common celadon and Mi’se celadon which unearthed from Housi’ao kiln site of Shanglin Lake, to realize the understand of element composition, microstructure, water absorption, etc. Meanwhile, a spectrophotometer has also conducted the tests of surface chroma on the common celadon and Mi’se celadon of Tang and Five Dynasties. The results of the analysis showed that the base of the common sagger was similar in composition to that of the porcelain sagger in the Tang and Five Dynasties, using local alluvial clay-like raw materials with a SiO₂ content of approximately 75% and an Al₂O₃ content of approximately 16%, similar to that of the celadon body. In contrast, the TiO₂ and Fe₂O₃ contents of the porcelain sagger in Tang and Five Dynasties were higher than those of the celadon body and fluctuated slightly, indicating a more rigorous process of washing the celadon body. The presence of a large number of inclusions of coarse particles with an average size of around 530 μm and a regular particle gradation in the common sagger was a type of high-silica material that was deliberately selected and added to increase the service life of the common sagger, increasing the permeability, mechanical strength and thermal stability of the sagger and thus extending the service life of the sagger; the porosity of the porcelain sagger in Tang and Five Dynasties was 1.61% and the water absorption rate was 0.73%, lower than the common sagger 8.18%, 4.28%, while the bulk density of 2.22 g·cm^-3 higher than the common sagger 1.99 g·cm^-3, and thermal conductivity than the common sagger, conducive to reducing the temperature difference between the inside and outside of the sagger, to alleviate the temperature lag phenomenon. In addition, the use of a porcelain sagger with a lower porosity and the sealing of the mouth rim at the Housi’ao site in Shanglin Lake effectively reduced the degree of secondary oxidation of the fired celadon glaze during the cooling process, improved the stability of the atmosphere within the sagger and the Fe²⁺ content of the celadon glaze layer, and improved its colour stability and appearance. At the same time, the slightly thicker glaze layer on the Mi’se celadon reduced the influence of the body on the appearance of the product and increased the refractive index and brightness of the glaze, placing it in a more bluish-green area in the CIE chromaticity space than common celadon.