This study investigates the deformation of Al-based metal matric composites (MMCs) under in-situ micro-pillar compression. Different sizes of SiC nanoparticles, namely 55 nm and 700 nm, were used as reinforcing medium in the MMCs. Such in-situ compression shows real time deformation of materials and helps to correlate materials’ response with corresponding stress-strain curves. It was shown that, MMCs exhibit higher yield strength compared to monolithic Al, thanks to effective load bearing among reinforcement and matrix. Whereas monolithic Al experience substantial work hardening, MMCs experience blocking of dislocations and slip/shear bands by the presence of reinforcing nanoparticle. These gives rise superior strength on MMCs compared to monolithic Al6061 alloy, which is about two times higher.