Masks have become an everyday item. Wearing a mask can prevent the inhalation of germs and other toxic substance. Surgical masks are generally worn by the general public. This pleat is large and the folds tend to be pulled flat on people’s faces, resulting in a small effective filter area and high breathing resistance. The authors registered a patent of a pleated three-dimensional filtration mask with a restricted drawstring structure to prevent the mask from being flattened on the face and reducing the filtration area, while at the same time, ensuring that the pleats of the mask are not flattened to form a three-dimensional filtration and ensure a large filtration area. In order to optimize the filtration structure of this new mask, a three-dimensional simulation model of mask breathing was established and the influence of pleat structure such as pleat interval, pleat height and pleat shape on the breathing resistance of the mask under different breathing conditions were investigated using CFD. Results show that this new mask could reduce the breathing resistance by about 40% under the premise of ensuring the filtration accuracy.