SiO2 matrix composites doped with AlN particles were prepared by hot-pressing process. Mechanical properties of SiO2 matrix composites can be greatly improved by doping with AlN particles. Flexural strength and fracture toughness of 30 vol%AlN-SiO2 composite sintered at 1400 degrees C reached 200 MPa and 2.96 MPa.m(1/2). XRD analysis indicated that, up to 1400 degrees C, no chemical reaction occurred between SiO2 matrix and AlN particles suggesting an excellent chemical compatibility of SiO2 matrix with AlN particles. The influences of hot-pressing temperature and the content of AlN particles on dielectric properties of SiO2-AlN composites were studied. The temperature and frequency dependency of dielectric properties of SiO2-AlN composites were also studied. Residual flexural strength of SiO2-AlN composites decreased with increasing temperature difference. The critical temperature difference was estimated about 600 degrees C.