we studied the micro mechanism of Anti-Stokes fluorescent cooling at molecular scale. The conception of "Single Molecule-Photon Cryocooler (SMPC)" was suggested for the first time. The viewpoint of cooling with one single molecular was clarified. One single molecule can be the smallest cryocoolcr when some special conditions are satisfied. We Investigated its running processes and charactors through analyzing the working principle of SMPC. At last
the key conditions that influencing on the SMPC's cooling efficiency of SMPC were discussed.