If your calendar isn't syncing to your phone first make sure
- You're connected to the Internet
- Your using the Google Calendar app and it is up to date
- Check that the calendar is visible
- Make sure new event are being added to your Google Calendar
If you're still experiencing issues please go to this link from Google
https://support.google.com/calendar/answer/6261951?hl=en&ref_topic=3417969