One of the goals in solid rocket motor design is to have as large volumetric loading as possible keeping the basic requirements unaffected. Slotted grain can achieve this goal as it has the advantages of sliver-free and no stress-concentration regions that occur in other internal burning grains as star grain and wagon wheel grain. It has the disadvantage of exposing the motor wall to hot gases. In this paper, the geometry of slotted grain is discussed and the effect of design parameters (e.g., number of slots, dimensions of the slot, etc.) of slotted grain on grain burn back is explained. Also, a comparison between results and experimental data is performed.