Abstract: In this work, two heat transfer models were established for an oven of rotational molding with adjustable vanes inside its inlet. One was the so-called “model without mould”, in which there was no mould inside the oven. The purpose for establishing this model was to theoretically study the relation of temperature uniformity of air inside the oven with turning angles of vanes. The other one was so called “model with a mould”, in which the size and rotation of mould were considered. The purpose for establishing this model was to theoretically study the relation of temperature uniformity of mould wall with turning angles of vanes. Based on these two heat transfer models, the heating process of rotational molding was simulated numerically by means of the FLUENT software. It was concluded that the temperature uniformity of air inside the oven was optimum when both lower and upper vanes were set at the horizontal direction, and the temperature uniformity at the wall of 2 m long mould was optimum when the turning angles of upper and lower vanes were set as 0 ° and 20 ° respectively. In addition, the simulation study also demonstrated how the temperature uniformity of mould wall varied with the mould length when both the lower and upper vanes were set at the horizontal direction.