Nanocomposites like other heterogeneous materials, are made from components that are completely separable with different physical and mechanical behavior. Interactions between components in nanocomposites creates interesting and sometimes incredible properties such as high strength to weight, improved mechanical and thermal properties of nanocomposites that is not available in ordinary materials Multifunctional behaviour of nanocomposites, increases the general tendency to this class of materials. Several experimental, analytical and numerical studies have been conducted to characterize the mechanical behavior of PCNs. However, the variation of material parameters and the stochastic nature of interphase region limit the use of deterministic methods. The main goal of the current study is to investigate the effect of interphase properties (thickness and mechanical properties of interphase region) on the mechanical properties of nylon6/clay nanocomposites. A combination of stochastic analysis and sensitivity analysis was used to evaluate important parameters. The sensitivity analysis results showed that the mechanical properties of interphase region has more effect than thickness on stress-strain curve of nylon6/clay nanocomposites. The mechanical properties of nylon6/clay nanocomposites such as elastic modulus, yield strength and stress-strain curve were calculated numerically. With an acceptable standard deviation to the experimental data, the numerical results show a good agreement with experimental results Keywords: Nylon6/clay nanocomposites, computational homogenization, interphase, sensitivity analysis, stochastic analysis