The polytetrafluoroethylene(PTFE)/woven glass fiber(GF) composite substrates were prepared by the hot pressing process under a certain pressure.The effect of the hot pressing temperature on the absorption,dielectric properties, coefficient of thermal expansion (CTE) and the morphology of the composites were systematically investigated.The differential scanning calorimetry (DSC) method was used to study the whole process of the composites manufacture. The morphology of the composites and the distribution of the glass fiber on PTFE was also comfirmed by fracture surface analysis of scanning electronic microscope.The Vector Network Analyzer was employed to study the dielectric properties. The research results showed that when the hot pressing temperature is370 ℃,the desired dielectric constant and low dielectric loss (εr=2.2，tanδ=8.7×10-4) were obtained in the hot pressing glass fiber/PTFE composites.Thermomechanical analysis was utilized to measure the coefficient of thermal expansion of the composites, and revealed the lowest coefficient of thermal expansion (160.1×10-6/℃@1~100 ℃) was obtained in the GF/PTFE composites under the hot pressing temperature of 370 ℃.