Closed-cell Al composite foam with high specific strength and high specific stiffness is a typical lightweight material, which has broad application prospectsSin the fields of automobile and aerospaceSapplication. However, the pore structure of aluminum foams prepared by traditional methods is difficult to control, which seriously hinders the production. In this paper, a new preparation process for closed-cell CNTs/Al composite foam based on friction stir welding was proposed. The microstructure and elemental composition of the CNTs/Al composite foams with different rotationSspeeds (1000-1300rpm) were analyzed by scanning electron microscopy and energy dispersive analysis (SEM/EDS). The temperature distribution of the CNTs/Al precursor foam was studied by infrared thermometer and numerical simulation. The mechanical properties of pure Al foam and the CNTs/Al composite foam with different porosity were compared and analyzed by the quasi-static compression test. The results show that when the rotary speed of the stirring is 1000rpm, the surface of the CNTs/Al precursor foam is smooth and dense. Simultaneously, a blowing agent TiH₂, a stabilization agent Al₂O₃ and reinforcedSphase CNTs are uniformly distributed on the cross section of the composite foam. The comparison between the foaming temperature of 680℃ and 700℃ shows that when the foaming temperature is 680℃ for 15min, the pore structure is uniform and mainly consists of circular pores. TheSmaximum pore diameterSisS0.48mm. Infrared thermometer and numerical simulation temperature field show that the temperature gradually decreases with the increase of the distance to the center of the stirring head, and the peak welding temperature is located in the stirring head which exhibits aSbowl-shaped distribution. The stress-strain curves of the CNTs/Al composite foam show the deformation characteristics combining brittleness and ductility at room temperature. When the porosity is 30.5%, the yield stress and platform stress values of the CNTs/Al composite foam are the largest. Compared with the pure Al foam, the yield stress of the CNTs/Al composite foam is increased by about 2-2.8 times, and the platform stress is increased by about 1.4-2.9 times.