High-viscosity melt has great potential for energy saving. A mathematical model was proposed on the heat transfer between the rotating roll and melt in a roll dry granulation system, and the relationship between the rotation angle and time was utilized to simplify the three-dimensional dynamic process to a one-dimensional static problem. Then, the influences of the roll material, dimension, rotational speed and the melt shedding angle on the system performance were investigated. Simulation results indicated that increasing the thermal conductivity or decreasing the wall thickness result in a higher cooling rate, but a more nonuniform heat flux distribution. Heat-resistant steel is a better choice than copper alloy. The optimum wall thickness is about 19 mm herein, and the rotational speed should be kept below 17 rpm. The overall exergy efficiency can be increased from 37% to 59%, when the melt shedding angle is changed from 120° to 28.8°.