Swollen legs and a pit when pressed are caused by more severe lower extremity edema, the most common cause of which is heart failure. The diagnosis can be confirmed with a Doppler echocardiogram combined with serum BNP and serum ions. If it is caused by heart failure, oral diuretics can be given with furosemide or spironolactone, or a combination. If the effect is not good, intravenous medication can be given to improve lower limb edema. Liver disease, kidney disease, and thyroid disease can all cause lower extremity edema, and the appropriate tests are also needed to make a clear diagnosis and then treat the cause accordingly.