Add all of the email addresses that you would like to invite to your Gmail or Yahoo email account.
Method 1: Using Import Feature
Create a circle to add your friends into. I created one called “Facebook Friends”.
Drag all of the people you want to be added to Google Plus into that group (you can select as many as you’d like at once).
Method 2 : Using Stream
Type your personal message in the stream and type all those email IDs in the Add circles to share with. Now after adding all those friends email ids to share with. Now with this post, your friends will be receiving Google Plus invitations also.