Hybrid membranes combining the merits of both polymer matrices and fillers have drawn extensive attention. The rational design of polymer-filler interface in hybrid membranes is vitally important for reducing the occurrence of void defects. Herein, imine-type covalent organic frameworks (COFs) were selected as the fillers due to their totally organic nature and multi-functionalities. Mussel-inspired dopamine-modified sodium alginate (AlgDA) was synthesized as the polymer matrix. The dopamine modification significantly improves the AlgDA-COF compatibility, which enhances the COF content up to 50 wt% in the hybrid membranes. The improved interfacial compatibility enhances the membrane separation selectivity. Accordingly, when utilized for dehydration of ethanol/water mixed solution (water concentration of 10 wt%), the hybrid membrane reveals high water concentration of similar to 98.7 wt% in permeate, and stable permeation flux larger than 1500 g.m(-2).h(-1). This work might afford useful insights for fabricating hybrid membranes with high separation selectivity by optimizing the polymer-filler interface. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.