It has been proved by long-term practice that pleated filter bags can solve the problem of increasing the filtering area without changing the main equipment and the floor area of the bag filter. However, the filtering performance of this folded filter bag is acceptable only when the number of folds is low. When the number of folds is high, the shortening of the fold spacing will have a certain impact on the filtering and ash removal. In order to study the influence of the change of pleat spacing caused by the increase of pleat number on the filtration performance of pleated filter bags, a new Y-shaped pleated filter bag is proposed in this study to explore the influence of multivariate geometric characteristics on the filtration pressure drop. The three-dimensional filter medium model of polyester fiber filter material is constructed by using GeoDict, and the filter medium penetration model is obtained for the macro numerical simulation of Y-shaped pleated filter bag. Based on the response surface method, the influence of multi structural parameters of Y-shaped pleated filter bag on its filtration performance is explored. The research results show that within a certain range of filtration velocity, GeoDict simulation can be used to replace the experimental test. And the filtration pressure drop of Y-shaped pleated filter bag is lower than that of conventional 8 and 16 pleated filter bags. Wherein, compared with the conventional 8-pleated filter bag the filtration area of Y-shaped pleated filter bag increases by 58.04% when the number of Y-pleats (NY) is 8, the opening angle (α) is 30°, and the concave diameter (d ) is 228 mm, and the outlet velocity distribution uniformity increases by 21.23%. The uniformity of outlet velocity distribution is 28.51% higher than that of conventional 16-pleated filter bag. The optimal structural parameter of Y-shaped pleated filter bag is NY=12, α=20.17°, d=240.18 mm, and the filtration pressure drop reaches the minimum value of 136.67 Pa.