The redness and swelling of the thigh, the first thing to consider is whether there is an infection of the tissue, because infection in the clinical performance of redness, swelling, heat, pain, this situation may be caused by local inflammation like cellulitis; there may also be the lower limbs or the root of the thigh has peripheral inflammation secondary to lymph node infection and redness and swelling. For these cases, the main clinical treatment is to give active anti-inflammatory treatment, in addition to local wet compresses of alcohol can be taken to reduce swelling. And if the inflammation is complicated by purulence, it may be necessary to incise and drain, and then antibiotic anti-inflammatory treatment. Next, we should consider whether there are mosquito bites that cause tissue allergy and redness, for this case, we should mainly give anti-allergy treatment, and give calcium gluconate or glucocorticoids to be pushed. Then we should consider whether there are varicose veins of the saphenous vein and deep vein thrombosis, if this is the case, we suggest that it is best to seek medical attention in order to clarify the diagnosis and timely treatment.