This paper focuses on effect of carbon nanotubes physical parameter on elastic modulus of nanocomposites. The remarkable properties of at least some of nano particles have led to high research in the field of nanocomposites, especially carbon nanotubes. In this paper, polymer matrixes and carbon nanotubes are interest. At the nano scale, the structure of the carbon nanotube strongly influences the overall properties of the composite. Some well-known theories such as Halpin-Tsai equation, shear lag model and modified mixture of low were employed to consider the efficient of carbon nanotubes physical parameter on elastic modulus of nanocomposites. According to the results, addition of volume fraction of carbon nanotubes caused a reduction of elastic modulus. The nanocomposite elastic properties are particularly sensitive to the nanotube diameter, with increasing on diameter and wall thickness of carbon nanotube the elastic modulus decreases and when length of carbon nanotube is increasing, the elastic modulus increases.
