Microwave ceramics of Ba(Mg0.2/3Zn0.8/3Nb2/3)O-3 and Ba1-xSrx(Mg0.2/3Zn0.8/3Nb2/3)O-3 were synthesized with conventional solid-state reaction method. Dielectric properties of the samples were studied as functions of compositions and sintering temperatures. Experimental results show that a higher Q x f value is reached by substituting Zn ions with Mg ions and a near-zero temperature coefficient of resonant frequency is obtained by replacing Ba ions with Sr ions