The perovskite (1-x)LaAlO3-x SrTiO3 dielectric ceramics were prepared by the solid state method. The sintering behavior, microstructure and dielectric properties of (1-x)LaAlO-xSrTiO3 ceramics were investigated in this paper. The results show that the main crystal phase shifts from the rhombohedral phase to the orthorhombic phase, and then changes to the cubic phase with the increasing content of SrTiO3. The dielectric constant εr and the temperature coefficient of resonance frequency τf increase with the increasing content of SrTiO3, and the dielectric losstan tan δ is directly related to the structural transformation. When x=0.46 and the ceramics were sintered at 1 550 ℃ for 4 h, the samples have good crystal grain growth, a compact structure and distinct grain boundary. The dielectric properties of εr=35.7, tanδ=3.01×10-4, τf=-14.6×10-6/℃ are obtained.