The synergetic effect of amine functionalized multiple graphene layers (AMGL) and multi-walled carbon nanotube (AMWCNT) nano-fillers mixed with epoxy resin is investigated on the particle size distribution (PSD) and tensile properties of hybrid composites. The hybrid composites with an equal ratio of nano-fillers at a weight percent of 0.25, 0.50, 1, and 2 wt % are fabricated. The particle size analysis (PSA) is performed by the dynamic light scattering (DLS) technique and image analysis (IA) method; both verify PSD for composites. This is further verified by the analyses of scanning electron microscopy (SEM) images using Image J software. The optimum composite particle size of 6.8 µm and homogeneous mixture with a poly-dispersity index (PI) of 0.74 is investigated for a sample having filler content of 0.5 wt %. Tensile stress and elastic modulus is also found to be maximum at 0.5 wt %, which is 49.91 MPa of 2302 Mpa, respectively. The chemical composition of composite affecting its PSD is characterized by energy dispersive X-ray (EDX) process. Dimensional analysis of particle size in the domain of epoxy matrix provides deep insights to the researchers and may also provide them a direction for selecting an appropriate material for a particular application.