Why does my female dog keep licking the penis of my little new male dog?

I think she is mothering him. Mother dogs work very hard to keep their pups clean.

Female dogs do that to male dogs all the time its normal

I have dogs that do the same thing ... She is probably trying to keep him clean!

If they're not neutered or spayed, then get that done immediately unless you want a lot of puppies soon...

shes probably cleaning it'