The TiO2 filled PTFE microwave dielectric composites were fabricated by means of the mechanical mixing,cold press and sintering. The morphology of the composites and the dispersion of TiO2 particles in PTFE were characterized by the scanning electron microscopic technique. Some important parameters such as thermal expansion coefficient，dielectric properties and moisture absorption were measured. The influences of TiO2 particles with different content on the thermal and dielectric properties of the TiO2/ PTFE composites were investigated. The results showed that with the content of TiO2 increasing，〖HJ*4/9〗the density of the composite increased to a maximum and then decreased,the moisture absorption,dielectric constant and loss tangent all increased with the content of TiO2 increasing, while thermal expansion coefficient showed the opposite trend. As the content of TiO2 increased to about 65%，the composites had dielectric constant 8.9 with loss tangent 0.002 5，and its density reached the maximum（2.802 g/cm3）.