In order to study the raw materials and technical processes used for ancient porcelains unearthed from Gongyi Kiln in Henan Province and Xing Kiln in Hebei Province, and also to investigate the technical connection between the two kilns, we selected the celadons and white porcelains produced in the Northern, Sui and Tang Dynasties and conducted microscopic observations and electron probe microanalysis (EPMA). The results indicate that there are some differences in the raw materials used for the bodies and glazes of porcelain samples from the two kilns. For Gongyi Kiln, local kaolin clay is the only ingredient used for porcelain bodies, whereas the glaze includes high-calcium (Ca) plant ash in addition to the raw material used in the porcelain bodies. In the case of Xing Kiln, local kaolin clay and feldspar mineral are used for porcelain bodies, and the glaze contains not only clay but also plant ash or minerals with high contents of calcium (Ca) and magnesium (Mg). However, the products of Gongyi and Xing Kilns still share some similarities, such as appearance and shape as well as the use of certain raw materials (e.g., addition of quartz mineral to the glaze). It can be inferred that Gongyi and Xing Kilns had close communications in terms of raw materials and techniques for porcelain making.