There are many factors that cause bedsores, first of all, from the mechanical factors to consider, resulting in pressure ulcers have three main physical and mechanical factors, as follows: 1, pressure, bedridden patients do not change the position for a long time, the local tissues continue to be under pressure for more than two hours, which can cause irreversible damage to the tissues; 2, friction, splints lined improperly placed, the plaster within the uneven or some of the debris, the patient’s long term bedridden or wheelchair skin can be By the surface of the retrograde resistance friction, resulting in decubitus ulcers; 3, shear force, closely related to the body position, by the two layers of adjacent tissue surfaces between the glide generated by the progressive relative friction, pressure added together. Secondly, physical and chemical factors, stimulation will cause bedsores, long-term pressure on the skin is often subjected to sweat, urine, fecal fluid all kinds of exudate, drainage fluid stimulation, sebaceous layer is damaged, skin tissue damage, breakage and infection induced bedsores. Systemic nutrition is very important, long-term bedridden patients, such as elderly patients with malnutrition, long-term fever and coma can not eat, paralyzed patients with malignant fluid poor nutrition, prone to pressure ulcers. Finally restricted patients, such as paraplegia, postoperative fracture patients, fracture, plaster bandage, deck and traction loose and tight discomfort padding is not appropriate, will cause localized bedsores.