The laser irradiation on Al-Si alloy sample is carried out by excimer laser in ambient conditions for 30 or 45 pulses. Microstructural investigation of laser treated sample is done by OM, SEM and TEM and the surface hardness is evaluated by Vickers micro indentation. Laser treated, samples suggested the dissolution of coarse primary Si and beta-AlFeSi particle in alpha-Al matrix. The SEM/EDS study shows the enhancement of retained Si in alpha-Al matrix. The interface analysis of laser treated sample suggested the effected modified depth is similar to 6 mu m. TEM investigation shows the formation of nanocrystalline Si in size similar to 2-15 nm. The cellular structures of size range similar to 30-50 nm are observed after 45 pulses. The alpha-Al cells and Si precipitates sizes were considerably refined at higher number of pulses. The fine Si precipitates are found to be dispersed in the intercellular boundaries. An improvement in surface hardness from similar to 1.6 to 1.8 is observed 30 and 45 pulse treatment, respectively. The mechanism involves for improvement in surface properties are non-equilibrium solidification, metastable phase formation and microstructural refinement. (C) 2016 Elsevier B.V. All rights reserved.