In order to reduce the diameter of meltblowing fibers, a new type of die head with an air accelerator was designed, and the influence of the structure of the air accelerator on the flow field below it was investigated. With the aid of Fluent software, the air flow field of the new die head was numerically calculated, and the air velocity and air temperature distribution law in the flow field were analyzed. The research results show that the structure of the air accelerator has a great effect on the performance of the flow field. When the distance between two air accelerators diminishes, the air accelerator height increases, the air accelerator inclination reduces, and the side of the air accelerator becomes an inner arc, the peak air velocity and the air temperature on the spinning line rise. By comprehensive comparison, under the conditions that the air accelerator half-spacing is 10 mm, the air accelerator height is 30 mm, the air accelerator inclination is 60°, and the side of the air accelerator is inner circular arc, the extreme value of air velocity and air temperature in the flow field under the new die are the largest.