It's plural.cuz in the friend(s) word, it contain s in the end of the word.it shows you that the word is plural

The phrase "none of my friends" is plural.

None = not one - not one of my friends is The verb should be in the singular "is" because the subject of the sentence is singular. However, you will hear the plural used "none are...." just as frequently and both are acceptable.

Sorry..typo correction to the above answer.: The majority of people would use a plural verb and say 'None of my friend smoke'.

I agree with Peter McK. If you check in a traditional grammar book, 'none' is actually singular. According to grammarians, 'none' is a contraction of 'not one' and is therefore a singular noun. So, strictly speaking, if you follow this rule, you should say 'None of my friends smokes'. However, very few native speakers follow, or are even aware of, this rule, and the majority of people would use a plural verb and say 'None of my friend smokes'. This is another of the cases where the so-called 'wrong' form sounds more right than the 'right' one does.