Hydrophobic poly(tetrafluoroethylene) (PTFE) flat-sheet membranes were prepared by a novel method with polyvinyl alcohol (PVA) as membrane carrier. Factors affecting PTFE membrane pore structure and mechanical properties such as sintering temperature, sintering state, and the simulate model were investigated. Results show that it was better to form pore structure at the first sintering stage. Morphologies of membranes were observed by scanning electronic microscopy (SEM). Membrane microvoids among the fibrils net nodes were loose by fixed setting sintering while compact by relax setting sintering. Chemical constitution and thermal stability of PTFE/PVA blend membrane after sintering (m-PTFE) and PTFE membrane were investigated, and no obvious difference in chemical constitution could be found between m-PTFE and PTFE membranes. The m-PTFE membranes obtained are still strong hydrophobic by the determination of contact angle to water.