Abstarct: In this thesis, we introduce the idea of actually cooling quantum systems by means of incoherent thermal light, hence giving rise to a counter-intuitive mechanism of “cooling by heating”. In the first chapter, we examine the tools of mechanical quantum that we need in brief and we get some knowledge from different noises; Since, the system under consideration is an open quantum system, it described by different approaches: the master equation (Schrodinger picture), the Fokker-Planck equation (phase space), the Langevin equations (Heisenberg picture). Here we are going to consider only the first approach in the second chapter. In the third chapter, we examine the opto-mechanical setup for “cooling by heating” and we get the master equation of it by using projection operators techniques. finally in the forth chapter, we get the state of mechanical mod by the use of similarities between the Hamiltonian of our setup and a beam splitter.