This paper reports the results of the chemical composition and phase structures of the Tang Sancai from the Xing Kiln and Ding Kiln. The research results show that the bodies of Tang Sancai came from the Xing Kiln and Ding Kiln have different sources and formulations.The most remarkable thing is that Ca glazeand Pb glaze are together in Tang Sancai sample XY4 from Xing kiln.On the other hand,the α-quartz and trace amounts of anorthite are commonly found in Tang Sancai in high-lead glazes both from the Xing kiln and the Ding kiln. Notably,there is mullite (3Al2O3·2SiO2) and a trace amount of α-Fe2O3 in Ding kiln yellow glaze. Besides,there is a trace amount of Pb8Cu(Si2O7)3 in Ding kiln green glaze;Furthermore,there is a small amount of potassium feldspar (KAlSi3O8) in the white glaze of Xing kiln.These trace amounts of crystalline phases are probably formed by complex physical and chemical changes during the firing and cooling processes or come from the glaze itself.It plays an important role in understanding the early Tang Sancai firing technology and authenticity identification and in further study of sources of Tang Sancai come from the tombs.