Abstract. It is well established that Quantum Chromo-Dynamics (QCD) at finite temperature exhibits a typical behavior of a system with a phase transition. At sufficiently high temperatures and/or densities, the strongly interacting matter undergoes a Deconfinement Phase Transition from hadronic state to Partonic state. This new state has been observed and identified as being the QCD partonic plasma in Ultra-Relativistic Heavy Ion Collisions experiments at RHIC and LHC. All hadrons created in the final stage of Ultra-Relativistic Heavy Ion Collisions experiments are colorless. When we insert the colorlessness condition in the MIT bag model, we obtain our Colorless QCD MIT-bag model using a mixed phase system evolving in a finite total volume V . As we know, the low-temperature phase of hot QCD is dominated by pions, and instead of taking a massless pionic gas, we take massive pionic matter then massive baryonic matter as two better descriptions of the hadronic matter. We will investigate the mass effect on the order parameter of the colorless deconfinement phase transition. The chiral symmetry, which is broken in the transition region due to hadronic mass, is restored at high temperature. The larger the hadronic mass, the slower is the restoration of the chiral symmetry, leading to the dependence of the finite volume transition point on the hadronic mass T 0 (V, m HG ). Our results are in complete agreement with the experimental data and predictions of other models.