Abstract： Huanghoite fBaGe(CO3)F] is a new mineral discovered in China. The parameters of the hexagonal unit cell have been determined as α=5.07?, c=38.6? by using electron diffraction method. The value of c is twice as large as that determined previously by X-ray diffraction analysis. Huanghoite is composed of atoms with large difference in atomic number. The advantage of electron diffraction in investigating such kind of minerals is discussed.The stacking faults along direction c have been observed by lattice imaging technique. The possille cause of formation of such faults is proposed.