To overcome the shortcomings of inefficiency in the preparation of covalent organic frameworks (COFs) nanosheets by ball milling, a gram-scale method to preparing COFs nanosheets with butyl lithium as the intercalation agent has been proposed. A significant advantage of COFs nanosheets that display good interface compatibility has been discovered through experiments. Due to their special organic crystalline structure and hydrogen bonding effects, COFs nanosheets without any modification show good interface compatibility, good dispersibility and enhancement in the mechanical properties of PVA matrix even at the loading as high as 9.6 wt%. Meanwhile, thermal, hydrophobic and flame retardant performances of PVA/COFs nanosheets nanocomposite have also been strengthened. This work should provide a guidance for the preparation of multifunctional nanocomposites with high loading. (C) 2019 Elsevier Inc. All rights reserved.