Abstract: xSrTiO3-(1-x) LaAlO3(x=0.4-0.7) dielectric ceramics were prepared by solid state reaction method, the structure and properties of ceramics with different x value were discussed. The results show that perovskite solid solution was the main phase of this ceramics. The perovskite were orthogonal structure and constrain cubic structure when x were 0.4-0.5 and 0.55-0.7 respectively. The ceramics with the pseudocubic structure exhibited the higher dielectric constant (ε＞50), lower dielectric loss(10-3-10-4)and near-zero temperature coefficient. The dielectric constant decreased obviously (ε=35-45) and dielectric loss increased rapidly (about 10-2)when the ceramics transformed from orthogonal structure to the constrain cubic structure. Good dielectric properties (ε＞55, tan δ of the ceramics was about 10-3-10-4 at 1 MHz)were achieved when x was 0.6 and 0.7. Excellent microwave dielectric properties of ceramic (x=0.4) were achieved as following: ε =30.5, Qf=40 177 GHz, τf = -22.9×10- 6℃-1.