Novel polyamide (PA) composite membranes were prepared by conducting interfacial polymerization on the modified carbon nanotube (mCNT)-deposited polyacrylonitrile (PAN) ultrafiltration membranes. Based on the characterization using TEM, SEM, FT-IR, and contact angle measurements, more even mCNT stacking could be realized on hydrolyzed PAN (hPAN) substrate. The uniformly stacked mCNT scaffold on hPAN is conducive to the formation of the PA composite membrane with a dense and crumpled texture. The prepared PA composite membrane exhibited dense crumpled texture with high hydrophilicity. The influences of surface morphology, feed temperature, and salt concentration and composition on desalination performances for PA composite membranes were investigated, followed by stability evaluation. Subjected to pervaporation desalination, the water flux attained to an ultrahigh value (104 kg m−2 h−1) with ideal rejection performance (99.99%) using 3.5 wt% NaCl aqueous solution as the feed at 70 °C. Moreover, the prepared PA composite membrane was also competent in hypersaline water desalination and acid brine water treatment. All the results demonstrated that the prepared PA composite membrane with crumpled texture had a great application potential in seawater desalination. Display omitted •Carbon nanotube (CNT) was partially unzipped to form modified CNT (mCNT).•Polyamide composite membranes were prepared on mCNT-deposited polyacrylonitrile substrates.•Flux reached 104 kg m−2 h−1 with 99.99% rejection to 3.5 wt% NaCl solution at 70 °C.•Prepared composite membranes exhibited long-term stability with acid-resistant ability.•Prepared membranes were competent in hypersaline water desalination by pervaporation.