Due to numerous difficulties associated with the experimental investigation of the single-walled carbon nanotubes (SWNTs), computational modelling is considered to be a powerful alternative in order to determine their mechanical properties. In this study, a novel three-dimensional finite element model incorporating a beam element with circular cross section is developed based on equivalent-continuum mechanics approach. The beam elements are used as the replacement of C-C chemical bonds in modelling SWNTs. Finite element models are generated for a range of SWNTs and employed for the evaluation of effects of diameter and chirality on the mechanical properties including Young's modulus, shear modulus, shear strain and Poisson's ratio of SWNTs. The results of this study are in good agreement with those reported in literature.