Micro-Raman measurements of xBa~Mg1/3Ta2/3)O3–(12x)Ba~Mg1/3Nb2/3)O3 perovskite ceramics, with x50, 0.25, 0.50, 0.75, and 1.0, were taken at room temperature. Raman results clearly show the 1:2 ordered structures of these compounds. Four A1g and ﬁve Eg Raman modes were unambiguously assigned. The A1g(O) phonon of the oxygen-octahedron stretch mode, which possesses the largest energy and width of all the observed Raman phonons, signiﬁcantly inﬂuences the microwave dielectric properties of the materials. A higher vibration frequency of A1g(O) mode results in a lower dielectric constant, and a wider width of the mode corresponds to a lower Q3f value.