Diamond wire saw is the first choice for the demolition of reinforced concrete walls and is expected to work from top to bottom for a couple of weeks. However, the service life of the machine is greatly affected by dry operating conditions. What’s more, the thick and high walls make the effective cooling of working diamond wire saws even harder. To tackle the cooling problem in the work, not only was the cutting heat generated during the cutting process calculated to provide a theoretical basis for the simulation and experiments, but the FEM software AdvantEdge was used to simulate the cutting process. By applying four different cooling media and comparing the temperature change of the cutting zone as well as the force of the diamond particles, the best cooling scheme was obtained. What’s more, the effectiveness of the cooling medium in the simulation process was experimentally verified. In the end, microscopic wear of the diamond particles was observed by Scanning Electron Microscope to study the impact of different cooling media. The proposed cooling scheme is of major significance for the dismantling of decommissioned nuclear facilities with diamond wire saws.