Abstract: Due to its superior properties, carbon nanotubes (CNTs) have been regarded as a promising reinforcement for the metal matrix composites (MMCs). How to fabricate the MMCs with homogeneous CNTs reinforcement is a hot research field. In the present study, the CNTs reinforced Al composite foams were successfully prepared through a combination of in-situ chemical vapor deposition (CVD), short time ball milling and the space holder method. The effects of ball milling time on the micro morphology, compressive property and energy absorption capacity of the CNTs/Al composite foams were investigated. The results show that with the ball milling time increasing, the microstructure uniformity of the composite foams is improved as a result of the enhanced CNTs dispersion in the Al matrix. Besides, the CNTs are deeply embedded inside the Al matrix after 90 min ball milling. Moreover, compared to the non-ball-milling 3.0wt% CNTs/Al composite foams, when the ball milling time increases to 90 min, the pore wall hardness, yield strength and energy absorption capacity of the composite foams are increased by 67%, 126% and 343%, respectively.