在DCMD中其結果顯示吐溫20為最合適的成孔劑隨著沉澱槽TEP wt%的比例增加，所製成的薄膜之通量皆會高於沒改質的薄膜，是由於隨著TEP在沉澱槽的比例增加薄膜表面皮層結構不易形成，且大孔洞數變多。且提高進料溫度能明顯增加滲透通量，但極化現象也較嚴重，而增加進料流率則對於滲透通量之提升較不顯著，但對於高溫進料操作之溫度極化現象具有較明顯改善效果。 In this study, the flat-sheet composite membranes of polyvinylidene fluoride (PVDF) supported on hydrophilic polyester were prepared, and their performances in direct contact membrane distillation (DCMD) for seawater desalination were also investigated. The simulated seawater of 3.5 wt% NaCl solution was adapted as the feed. The dope solution consisted of PVDF, Triethyl phosphate(TEP) and Tween20 or Tween80, and four conditions, 20、40 and 60 wt% TEP solution were applied in the coagulation bath. From the observation by SEM, the surface pore size of membrane increased with the increasing of TEP concentration in the coagulation bath. The experimental results of DCMD showed that tween20 is more appropriate to prepared this membrane. And the membrane prepared from higher TEP concentration had a larger permeate flux because of its larger pore size on the surface. And increasing the feed temperature of the feed can significantly increase the flux, but the polarization phenomena become more serious, but the effect of increasing feed flow rate the effect is not obvious on the flux.