Abstract: Multi-walled carbon nanotube (MWCNTs) was treated by a concentrated acid, then the acidified carbon nanotubes was co-spun with polyamide (PA66) to prepare MWCNTs-PA66 fiber membrane. An o-CFER/MWCNTs-PA66 composites was prepared through co-cured with the o-cresol formaldehyde epoxy resin (o-CFER), and the microstructure, mechanical and thermal properties were characterized. The diameter of PA66 fiber was increased with the addition of acidified MWCNTs. The impact strength and tensile strength of the composites increased firstly and then decreased with increasing content of carbon nanotubes. When the MWCNTs mass fraction was 0.5 % (based on the mass of PA66), the impact and the tensile strengths reached their maximum value 0.29 kJ/m2 and 1.96 MPa, respectively. The impact strength increased by 23.2 % compared with o-CFER resin, and increased 16.3 % compared with PA66/o-CFER composites. Tensile strength increased by 74 % compared with that of o-CFER resin. The thermal performance was improved when the MWCNTs-PA66 fibers membrane was added.