Abstract: To investigate the effects of the distance between air inlet and outlet in pallet, the number and layout of air inlets and outlets, and the diameter of air outlet on internal cooling time, a numerical simulation was carried out for the internal cooling process of rotational molded pallet by use of the Fluent software. The results indicated that the increase of the distance between air inlet and outlet led to a decrease in internal cooling time. In order to obtain a better internal cooling effect, the total area of air inlets should be larger than that of air outlets. In the cases of one air inlet and one air outlet, the internal cooling time was shortest when the outlet diameter was reduced to 79 % of the inlet diameter. However, the internal cooling time increased dramatically if the outlet diameter was smaller than this value.