if my iphone require a passcode and i am in accident how can they find my contact

If an emergency, you can make an emergency call whether your phone is locked or not.

Print it out and keep it in your wallet? Seriously, I would not depend on any electronic device for such vital information. I keep a hard copy in my wallet with my license and other ID.

Or, make your own custom lock screen wallpaper with an emergency contact information - that way they can see it without knowing the lockcode.

Without the passcode, that cannot be obtained from your iPhone. You will have to carry contact information is some other form, such as written down in your wallet.

You can make wall paper and put emergency contact information on it. There are app that will do it for you, too. Road ID is one.

https://itunes.apple.com/us/app/road-id/id569352341?mt=8

you can now set up an Emergency Contact in 'Medical ID' in the Healh app. When someone goes to the lock screen and switched to the Emergency call, they can click on the link Medical ID and then contact your emergency person. It also lists your age, allergies, and illnesses if you need it to.