The structure stabilities of double perovskite ceramics- (1-x) Ba(Mg1/2W1/2)O-3+xBa(Y2/3W1/3)O-3 (0.01x0.4) have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Raman spectrometry in this study. The microwave dielectric properties of the ceramics were studied with a network analyzer at the frequency of about 8-11GHz. The results showed that all the compounds exhibited face-centered cubic perovskite structure. Part of Y3+ and W6+ cations occupied 4a-site and the remaining Y3+ and Mg2+ distributed over 4b-site, respectively, and kept the B-site ratio 1:1 ordered. Local ordering of Y3+/Mg2+ on 4b-site and Y3+/W6+ cations on 4a-site within the short-range scale could be observed with increasing Y-doping content. The decomposition of the double perovskite compound at high temperature was successfully suppressed by doping with Y on B-site. However, Ba2Y0.667WO6 impurity phase appeared when x>0.1. The optimized dielectric permittivity increased with the increase in Y doping. The optimized Qxf value was remarkably improved with small amount of Y doping (x0.02) and reached a maximum value of about 160000GHz at x=0.02 composition. Further increasing in Y doping led to the decrease in Qxf value. All compositions exhibited negative (f) values. The absolute value of (f) decreased with increasing Y-doping content. Excellent combined microwave dielectric properties with epsilon(r)=20, Qxf=160000GHz, and (f)=-21ppm/degrees C could be obtained for x=0.02 composition.