1. On your iPhone home screen, tap “Settings” application.
2. Next, tap “Mail, Contacts, Calendars”
3. Tap “Add Account….”, followed by “Microsoft Exchange”.
4. In the Email field, enter the name of the Google account.
5. Leave it blank for the “Domain” field.
6. Enter your Google Account email address for the “Username” field.
7. For “Password” field, type in your Google Account password.
8. Tap “Next” at the top of your screen.
9. Next, a new “Server” field will show up. Enter “m.google.com”.
10. Tap “Next” at the top of your screen again. You may be prompted with a warning message. Just “Accept” it.
11. Select the “Contacts” and “Calendar” for sync. Presently, the “Mail” option is not supported yet. So, only enable “Contacts” and “Calendar”.
12. Tap “Sync” to confirm the synchronization and then tap “Sync” again for the data loss warning.
That’s it. Google Sync should now erase all your Contacts and start synchronizing them from your Google account. So, if you go to “Contacts” on iPhone, you may find it empty. But don’t worry. Wait for a while and you’ll see the Contacts come up after complete the Sync.

Did it myself and working fine 🙂
credit to SIMON NG