I am 22 week in pregnancy, I have edema in both lower limb (below knee) after almost 2 hrs standing or walking, I've no dm or hypertenstion, what I do?

Many possibilities. Some causes of swelling of the legs can include systemic problems such as hypertension, and problems with the kidneys and localized issues such as arthritis, infection, lymphatic obstruction, blood clots, varicose veins, trauma (fracture, sprain, tendonitis) and side effects to medication. Have it evaluated by a professional and get the appropriate treatment.
Diuretic. Eat cucumbers and dichon root. They are natural diuretics and will help your body to get rid of excess water.