Chalcogenide, which is a raw material for lenses, is an amorphous polymer and has thermal properties called glass transition temperature. Using these properties, press molding is performed through a molding machine, and the molding machine goes through sequential processes of 'preheating process' and 'forming process'. In order to produce a high-quality lens, the raw material have to heated to near the glass transition temperature. Therefore, this study confirms the temperature distribution of lenses and molds through heat transfer analysis in the process of forming infrared aspherical optical lenses. As a result of the heat transfer analysis, it was confirmed that the minimum temperature of the mold and lens was heated above the glass transition temperature during the 'preheating process', and it was confirmed that the minimum temperature of the mold and the lens was pressed at a temperature sufficiently higher than the glass transition temperature during the 'molding process'. Additionally, a thermal flow analysis was performed on the non-Newton fluid whose viscosity changes according to the thermal shear rate. Through this, the formability of chalcogenide glass was identified, and optimal temperature and pressure conditions were identified.