There are many clinical causes of arm swelling, such as infection, blood clots, trauma or overexertion, cardiac and renal insufficiency, etc. 1, trauma or overexertion: especially after collision by external force, it may lead to bruising and swelling of bones, muscles, tendons, ligaments and other multiple tissue structures, and it will also stimulate peripheral nerves, and painful symptoms will be more obvious when moving the arm; 2, infectious factors: due to the breakage of the skin of the upper limb leading to retrograde infection of bacteria, causing infection of the lymphatic network, manifested as erythema with clear borders, accompanied by upper limb 3.Thrombosis factor: after the appearance of deep vein thrombosis in the arm, the venous return is affected, and when a large amount of venous stasis accumulates in the distal tissues, it leads to obvious swelling in the arm, and also stimulates the peripheral nerve structures and causes pain; 4.Lymphedema: blocked lymphatic fluid return in the upper limb causes soft tissue fluid in the After repeated infections on the body surface, the subcutaneous fibrous connective tissue proliferates and fat hardens, which manifests as arm swelling and rough skin; 5. Also in the case of renal insufficiency will affect the normal water and diuretic functions, thus appearing swelling of the upper limbs.