Whenever i want deliver a speech in public, i feel extremely anxiuos and my heartbeat will increase , stress and nervous, but disappear immedietly after.

Public speaking: Public speaking is the most common phobia people have -- even more common than fear of death! so you are not alone. Some people do a form of "exposure therapy" by repeatedly giving public talks until the fear extinguishes to a bearable degree (groups like toastmasters, for instance). For more intense phobias, cognitive behavioral therapy with a psychologist will help even more. Good luck!

Performance Anxiety: Millions of people have this problem. Many of them use Propranolol in small doses to blunt the physical symptoms that appear during this anxiety.