This thesis deals with the deconfining phase transition of a finite system, using a simple model of coexisting hadronic gas and QGP phases in a finite volume. The infinite matter equations of state of the two phases are first used, and the finite size effects on the deconfinement phase transition are investigated by probing the behavior of some characterizing quantities near the transition. It turns out that in a finite system, all singularities occurring in the thermodynamic limit are smeared out and the transition is perfectly smooth. Secondly, the color-singletness requirement is imposed for the QGP phase, to satisfy the color confinement property of QCD, introducing an additionnal finite-size effect. A finite-size scaling analysis is then carried out to determine the scaling critical exponents, in a numerical way.