Lack of fitness in equipment and accessories of task force is one of the undeniable causes of death on the battlefield, because this equipment is transported a long time by the task force. If the equipment is not designed to fit the user's physical dimensions, musculoskeletal problems created for the soldier. One of the equipment that goes with soldiers is military backpack. An appropriate design of this device and its adaptation to the users’ needs and physical characteristics is very important. Backpack, although like all kinds of weapons does not have a direct role in combat, but its improvement cause less fatigue and damage and faster action among soldiers. In this article, it is trying with the literature review and interviews with experts to gather the most important factors, especially those that are considerable in the world equipped armies, and then with a view to "design" be analyzed. Finally, with aggregation and analyzing the critical factors affecting the military backpack design and assessment of existing models, the preliminary designs to choose the appropriate military backpack for multi-day operations are introduced and superior design with the main features of the distinction is presented.