Abstract: In order to determine the authenticity of a Dushan jade sample, it was analyzed by thin section identification, XRD powder diffraction and electron probe analysis. The test results showed that the sample was composed of illite and a small amount of sericite without plagioclase, mica and any other mineral phases that constitute Dushan Jade, implying that it was a counterfeit product. In addition, combined with the microscopic identification characteristics and electron probe analysis results, the author preliminarily concluded that the emerald green color present in the sample was due to the coloration of iron element. This counterfeit product is similar in appearance to Dushan Jade, and the conventional gemological parameters are also similar. But the hardness of the former is lower than that of Dushan Jade. Since the hardness test is a lossy test, it is recommended that the testing organization apply the infrared spectrometer for daily inspection.