Symmetry determination by CBED has been carried out for LiZnTa3O9 and LiGaTa3O9 crystals, which were first grown in our laboratory, LiZnTa3O9 is rhombohedral with lattice parameters, a=0.557 nm, a=56.12°,The point group is 3m and the space group is R3c. LiCaTa3O9 is tetragonal with lattice parameters a=0.778 nm, c=0.783nm. The point group is 4/mmm.