One of the factors affecting the performance of fiber-reinforced polymer composites is quality of stress transfer at the fiber-polymer interface in composite. Structure and properties of the fiber-polymer interface are the most important factors for load transfer between fiber and polymer matrix. Which, they can influence the mechanical properties of the obtained composites. The main objective of this work is studying the effect of nanoparticles type and structure on mechanical interlocking at the fiber-resin interface in order to achieve composites with desired mechanical properties. For this purpose, four nanomaterial's with different structure and properties including silica nanoparticles, silica aerogel particles, silicon carbide nanoparticles and silicon carbide nanowhisker were used and micromechanical (i.e. small drop test) and macro mechanical (i.e. tensile, bending and shear punching tests) properties of glass epoxy composite in the presence of these nanomaterials were investigated. The multivariate statistical analysis at a significance level of 0.5 was used to evaluate the statistical analysis of results. The results showed that the nanowhisker enhanced 17.36% and 38.55% the tensile and flexural properties of composite, respectively. Also, the shear strength in small drop test and shear punch test were enhanced 30.89% and 38.13%, respectively. The obtained results of the tensile test were verified using mixing law relationships, Chamis and Halpin-Tsai .Also composite tensile test simulated with the finite element method and fabric model with component yarns and the effect of interlocking were considered. Finally, Finite element method showed the best fit with the experimental results. Key Words : interphase, micromechanical test; macro mechanical test, nano particle, mechanical interlocking