Is it possible for me to increse my height at age of20?

Almost never happens: Most people reach their maximum height in their late teens. Without nutritional problems or chronic childhood illnesses, height is largely based on genetics and parental heights. Aside from eating right, exercising, sleeping well, and being happy, there's not much a person nor his doctor can do to increase height. In rare cases, growth hormone is approved for use in younger, extremely short kids.