Sorry if this is already asked by some1,
as I rmb I heard of this before, but dunno is it just a scam...
is there any BTC wallet there will provide you interest?

Some exchanges provide you interest because they can work with the money or other users need it for margin trading.
I advise you to be careful if you find a wallet that gives you interest (mostly smaller wallet providers) or give it a try with just a few Bitcoins to start/test.