To clarify whether the Si particles rotate with respect to the matrix grains during tensile deformation of Al-Si alloys, in-situ tensile SEM and ex-situ EBSD were coupled to investigate the relationship between Si particles’ rotation and grain rotation. By comparing the on-plane projection of 3D orientations of grains revealed by EBSD and in-situ SEM observations of Si particles during deformation, noticeable relative rotation of Si particles on the sample surface plane with respect to the matrix grains was found. Besides, greater relative rotation of the Si particle was found to introduce a higher density of geometrically necessary dislocations (GNDs) which can cause work-hardening effects in the matrix nearby the Si particles, according to kernel average misorientation (KAM) analysis of EBSD data. In summary, the larger relative rotation of Si particles can cause higher work-hardening effects.