A polymer melt is simulated at finite temperature by the Monte-Carlo method. We use a coarse-grained model for the polymer system, the bond-fluctuation model. Static properties of the melt can be obtained by generating configurations not with single-monomer-dynamics which moves individual monomers locally, but reptation-dynamics which allows collective motion of the chains. This algorithm can produce equilibrated configurations much faster. It is demonstrated that static properties do not differ from those obtained by single-monomer-dynamics. Values of the radius of gyration, the mean square bond length and similar quantities for different temperatures and densities are presented