Recently, numerous efforts have been focused on the size-dependent Youngs modulus of nanocrystals, nanostructured materials and nanoalloys as it is one of the most fundamental parameters to describe the elasticity of a material.In this work, a nanotherrmodynamics model was established to investigate the Youngs modulus of nanomaterials by considering the size, dimensionality, composition and temperature effects.The accuracy of the developed model is assessed through comparisons with experimental data and other theoretical results available in the published literature and the intrinsic factor that dominates the variation of Youngs modulus in nanomaterials is revealed.