The purpose of this study is to provide some fundamental understanding for the design of industrial hollow fiber pervaporation membrane module. Inner skin hollow fiber pervaporation membrane modules were fabricated by a dynamic negative pressure layer-by-layer (LbL) technique. The influences of dynamic negative pressure and recycling velocity of polyelectrolyte solutions on the formation of non-porous selective layer were firstly investigated using mini-modules during the dynamic assembly process. Since none of reported works dealt with the effects of packing density of hollow fiber module, pilot-scale modules (diameter x length = 1 in. x 20cm)were therefore prepared by filling different amounts of hollow fibers into a membrane shell. The experimental results show that the higher packing density of 500 m(2)/m(3) rendered both total flux and selectivity to decrease significantly. As for a I m long module that has been commonly used in industry, further investigations were conducted using a 1-m long hollow fiber module. The vacuum drop along the axial direction of hollow fibers was noted, especially near to the vacuum suction opening. Despite of this, the relatively high and stable selectivity could be obtained even the fiber length increased to 1 m. (C) 2009 Elsevier B.V. All rights reserved.