Abstract: Hyriopsis cumingii is chosen as the pearly mussel. The gemmological characteristics of the northern pearl produced from Liaoning Province of China were investigated, with the help of hydrostatic weighing method, X-ray powder diffraction, Fourier transform infrared spectroscopy and scanning electron microscope. The testing results show that the relative density of the northern pearl of China is from 2.722 1-2.733 5. The mineral components of the northern pearl of China are aragonite and protein. The structure of the northern pearl of China is characterized as a form of “brick wall”. The thickness between aragonite layers of the northern pearl of China is 170 nm.