The work aims to build a model of the oven of wall-paper packaging machine and analyze it, so as to optimize its structure. Based on the fluid mechanics, the energy equation and kinematics equation of the heat-shrinkable oven were established. Through numerical calculation, the oven flow field distribution and simulation cloud chart were obtained. And then the flow field distribution of oven nozzle, bottom surface and return air inlet as well as its effects on heat shrinkage were researched. According to calculation results, the size and structure of return air inlet were improved and optimized, a variety of proposed improved structures were analyzed and calculated, and the relatively optimal model was determined by extracting and comparing the calculation results. Finally, the optimal improved model was applied to the oven for integral simulation and calculation. The optimized calculation data were extracted to complete the optimal structural design. In conclusion, the oven structure of the improved wall-paper packaging machine to some extent has improved the deficiencies in the original structure, which can better meet the process requirements in wall-paper packaging engineering.