The first aid technique for trauma site should be decided according to the specific trauma situation. 1.There is a possibility of bleeding from skin and subcutaneous tissues, sterile gauze and sterile dressing with pressure should be applied immediately so as to avoid the increase of local bleeding. 2.There is a possibility of fracture, if the fracture end is displaced, the injured limb should be fixed with splint or roadside branch. If the fracture is dislocated, the injured limb should be fixed with a splint or a roadside branch to avoid further displacement of the fracture and to prevent huge damage to the surrounding nerves and blood vessels, which may cause serious consequences. 3, there is a possibility of arterial rupture, which requires immediate pressure bandaging or pressure at the proximal end of the vascular injury. This can effectively block the loss of arterial blood to avoid hemorrhagic shock.4. If there is a respiratory arrest, chest cardiac compressions should be performed immediately, together with mouth-to-mouth artificial respiration to maintain the basic function of the heart and lungs.