The temperature profiles of a rectangular thin film heated with a scanning strip heat source are calculated using the Green function. Two boundary conditions are considered. One has both upper and lower surfaces insulated and the other has the upper surface insulated with the lower surface maintained at constant temperature. When the length of thin film along the scanning direction is infinity and temperature reaches steady state, the effect of scanning speed and specimen thickness on the temperature profile is investigated. The result is applied to an A4 paper sheet. Both the temperatures of the upper and lower surfaces are affected by the scanning speed, Gaussian radius and absorption depth. The criterion of paper feed to avoid paper curling is proposed.