The original firing conditions of the Yuan Dynasty Ru porcelain samples were stu-died by Mossbauer spectra. The result showed that the Ru porcelain glaze was fired in re-ducing atmosphere and the original firing temperature was deduced to be about (1150±50)℃. The Ru-porcelain body was found to be fired in stronger reducing atmosphere and it original firing temperature was also about (1150±50)℃.