The compound hydrostatic box is the key equipment to ensure that the lithium-ion battery separator material is dried uniformly in the drying room.Taking the compound hydrostatic box in the hot air heating system as the research object,the internal flow field of the compound hydrostatic box was studied by combining CFD with experimental research,and the influence of the structural parameters of the compound hydrostatic box on the outlet speed deviation was calculated and analyzed,and the structural parameters of the compound hydrostatic box were optimized by orthogonal experimental design.The upper and lower hole misalignment distance,inducer length and hydrostatic box width were analyzed and optimized.The results show that the air outlet speed uniformity and temperature uniformity of the optimized compound hydrostatic box are reduced by 0.085(17%) and 0.000 68 (26%) respectively compared with the original values.