Abstract: The surface hydroxylation of multi-walled carbon nanotubes (MWCNT)was conducted and then grafted with polyurethane to prepare soft composite foams by in-situ polymerization. To improve the interfacial interaction between MWCNT and polyurethane, an ultrasonic treatment was carried out to make MWCNT well dispersed in polyether polyols. The results indicated that the pores of polyurethane foam kept a stable shape with a uniform distribution and small size at the content of MWCNT lower than 0.4 wt%. A membrane structure was observed between the reticular foam walls. The bubble became larger and even collapsed when the content of MWCNT is higher than 0.6 wt%, The resilience, tensile strength and elongation at break of the composite foams exhibited an increasing trend at first and then tended to decrease with an increase of MWCNT content. The adsorption capacity of the composite foams was also influenced by the introduction of MWCNT, and their adsorption molar mass of strong polar water decreased with an increase of MWCNT content. However, there was an opposite trend for the adsorption molar mass of non-polar petroleum ether.