How to extend warranty of iphone ?

Check these links. They contain the AppleCare+ options.

http://www.apple.com/support/products/iphone.html

http://www.apple.com/support/products/faqs.html

You can purchase AppleCare+ to extend the warranty to 2 years within the first 60 days of purchasing the phone from an authorized retailer.

No, it needs to be purchased within the first 60 days of ownership.

9999803342 wrote:

Actually warraty of my iphone is about to expire in next week, so ?

So... your warranty will expire. It's way too late to try and extend it at this point.