Polymer nanocomposites have attracted the interest both from industry and academy. It is found that liquid-like polymer will exbihit solid-like behavior as the concentration of filled particles increases due to the formation of particle network. In this work, we will study the linear viscoelastic behavior, which represents the structure of nanocomposites. The contributions from polymer, hydrodynamic interaction and particle cluster (or network) are seperated. Then, the critical condition on the destroy of the structures are studied, and its dependence on the polymer properties and processing condition is discussed. Finally, the strong nonlinear transition from solid-like to liquid-like under flow field will be studied. The stress contributions in linear and nonlinear conditions are compared.