If the patient has a double leg swelling, it is the following factors: 1, the most common factor is infectious factors, when the patient has a bacterial, viral or mycoplasma and other pathogenic microorganisms infections, the lower limbs will appear red, swelling, heat, pain, joint dysfunction, accompanied by localized inflammation resulting in the development of foci of the situation. In severe cases, there will be skin ulcers, or even rashes, dengue and so on.2. Connective tissue diseases, especially rheumatic diseases, rheumatoid diseases, can cause swelling of the legs due to rheumatism factor.3. Lower extremity vascular diseases can also cause swelling of the legs, such as venous embolism or phlebitis of the lower extremities.4. Renal and cardiac insufficiency patients can also experience swelling of the lower extremities.5. Patients with renal insufficiency and cardiac insufficiency may also experience edema and swelling of the lower extremities, leading to the clinical symptom of distention.