Poly (L-lactic acid) (PLLA) flat sheet membranes with infer connected pores were prepared via nun solvent induced phase separation process. Polyethylene oxide (KO) with molecule weight of 100 kD was used as additives. The morphology evolution from the partial to total inter-connected pores in cross section was accomplished by adjusting the FED concentration. Besides, the effect of different molecule weight of polyethylene glycol (PEG), high coagulation intensity, different mass fraction ratios of FED to PLLA and the casting solution exposure time in air on morphologies of PLLA membranes were also investigated respectively. Finally, as a hemodialysis membrane, the water permeability, solute clearance rate and mechanical properties were detei mined. it was shown that PLLA membrane with highly inter-connected pores exhibited a higher water flux of 225 L/hm(2) and tensile strain of 83%. The clearance of the as-prepared membranes to urea and lysozyme is 77% and 33% respectively, while keeping BSA rejection with 90%. (C) 2015 Elsevier B.V. All rights reserved.