Abstract: In this paper, the cooling process of film blowing of Polylactic Acid (PLA) was studied. The temperature at the outside surface of the bubble was measured as a function of vertical distance from the die by an infrared pyrometer. The heat transfer coefficient (h) was studied at different airflow rates (Qv=0,0.66,1.33,2L/s) and different BUR (BUR=1.7,2.3). The correlation between heat transfer coefficient and axial distance is also reported. The results show that: the temperature decreases faster as the airflow rate increases; the heat transfer coefficient changes so small at lower airflow rates; the heat transfer coefficient inside the air ring are higher for higher airflow rates at higher airflow rates; the temperature decreases faster as the BUR increases and the heat transfer coefficient inside the air ring are higher for higher BUR; the heat transfer coefficient (h) is a function of the axial distance (Z) at different airflow rates.