In any case, if you are sure you are about the girl and feel that she is an integral part of your life and makes you happy, your parents should know about her. They should know that you’ve chosen someone really great and that they have nothing to worry about when it comes to your relationship.
If you think your parents will disapprove of her then it's best to take things slowly. Mention her name and how much you like her before you actually tell them that you're dating her.