I have renamed some of the pages of my website, but Google still showing old URL in SERP. so what should i do so that Google index new URL and show in SERP.
Did u do a 301 redirect old urls to new urls? if not then do this and wait for some time Google will index and display your new URLs. meanwhile you can get backlinks for new URLs.
Did previous URL had any PR? If you want to remove the previous URL from search engine, you can submit that links in webmaster tool and resubmit the sitemap as well.
If your Analytics shows referrals from other sites (such as a blog, article or forum) and they send a reasonable proportion of traffic, contact them directly and ask them to replace the old URL with the new one.