I want to create a new contact list just like blacklist to store few phone numbers in android. which storage medium we need to use ??
Do you wish to store them seperately from the main phone contact list? If so, user your own database. If not, consider adding some tag/attribute to contacts in the phone's contact list - you can then use this to identify your contacts later.
Also, if you're storing a list yourself and intend to store standard contacts in it, you'll need to make sure you have some unique mechanism for linking your contact the the phone's (what if someon changes name/phone number/???)
Without more information, it's not possible to give a comprehensive answer