The structure，performance and characteristics and the applications in archaeology of a new micro-X-ray fluorescence system based on rotating anode X-ray generator and polycapillary X-ray optics has been introducted in this paper. The polycapillary X-ray optics used here can focus the primary X-ray beam down to some tens of micro meters in diameters that enables non-destructive local analysis of sub-mm samples with minor/trace level sensitivity. In order to prove the potentials of this instrument used in archaeology， a piece of Chinese ancient blue and white porcelain produced in Ming Dynasty was analyzed. The results showed that intensities of MnKα，CoKα lines varied in accordance with the thickness of blue glaze. Correlation analysis indicated that the Mn and Co have good linear correlations. So，the concentrations or ratio of Mn and Co were crucial to determine the provenance of a Chinese ancient blue and white porcelain or to descriminate the true one from a fake.