For the purpose of improving the external ballistic performance of the existing multi-pulse solid rocket motor and make it better applied to UAV projectiles, a new honeycomb combustion chamber structure composed of seven hollow hexagonal prisms is proposed. The structural design method of the combustion chamber was proposed, and the calculation formula of the variation law of the combustion perimeter and the ventilation area of the charge column with the combustion thickness was derived, and the ignition criterion at work was analyzed. Under the same technical requirements, the external ballistic characteristic parameters of honeycomb combustor and axial dual-pulse combustor were compared. The design and calculation results show that the honeycomb combustion chamber can meet the requirements of multi-stage pulse thrust. The structural parameters of the combustion chamber have an influence on the performance of the rocket. The larger side length of the combustion chamber is helpful to increase the range and coverage of the rocket, while the larger grain length is helpful to reduce the minimum range of the rocket. Under the example taken in this paper, the range of UAV projectile with honeycomb combustion chamber is 71% larger than that with axial double pulse combustion chamber. The maximum range is increased by 28%, the minimum range is reduced by 44%.