BaR2Ti4O12(R denotes the rare earth)series solid solutions have excellent microwave dieletric properties.In particular, Nd-system materials have high dielectric constant(εr) and high quality factor(Q×f).This work investigated the influence of different molar ratio of Nd/Bi on the structural properties of the microwave dielectric ceramics of Ba0.75Sr0.25(NdxBi1-x)2Ti4O12. When x=0.75,that is,the molar ratio of x∶(1-x)=3∶1(abbreviated as B13),this material shows excellent dielectric properties with εr=118.5,Q×f=4 607(f=2.8 GHz),and the temperature coefficient of resonant frequency τf=-1.3×10-6℃-1.XRD patterns show that the main crystal phase of all the ceramics with different Nd/Bi ratio sintered at 1 250 ℃ to 1 400 ℃ for 3 h has main BaNd2Ti4O12 with small amount of second phase Ba2Ti9O20.SEM photographs suggest that Bi working as sintering aids promote the densification and grain growth of the ceramic samples.With the decrease of Nd/Bi ratio,εr increased slowly τf approached to zero gradually and moved to the negative direction while the Q×f value decreased.