Molecular-dynamics simulation has been used to investigate structural, elastic and thermodynamic properties of tin in the temperature range from 200K up to 286.36K. Calculations are carried out using the inter-atomic interactions model like a three-body potential of Tersoff. In the present work, a special interest has been made to the first form of tin (α-Sn), the reason why the temperature is below 286.36K. The calculated results of the lattice constant, the bulk modulus and its derivative, the total energy, and the pair distribution function are correctly described, in excellent agreement with other theoretical works as well as the experimental results. Our study enabled us to predict the thermodynamic properties like the specific heat and lattice thermal expansion.