Ni(400)/Al, Ni(1500)/Al and Ni(6500)/Al composite materials were fabricated by adding 30~40 μm, 8~10 μm and 2~3 μm Ni powder to the Al substrate in the friction stir processing (FSP) period. The microstructures of the surface composites were analyzed by SEM and EDS, while the phase composition was examined by XRD. Results show that Ni powder particle size has a great influence on morphological characteristics of their products. As the powder size increases, the aggregation effect becomes weaker while the crushing effect is enhanced. And Ni aggregation in Ni(6500)/Al, Ni(1500)/Al and Ni(400)/Al present an unique laminated structure, a nearly elliptic structure and a nearly circular structure, respectively. The increase of powder size is more conducive to the intermetallic compound reaction. Moreover, compared with the matrix, the tensile strength of Ni (6500)/Al, Ni(1500)/Al and Ni(400)/Al is increased greatly by 50%, 59% and 71.9%, respectively.