Do the links in comments have effect on blog

Generally speaking, it's bad. That's not because comment links (usually the name of the commenter is linked to the URL they supply) are intrinsically bad but because they're usually abused by spamming scumbags. This means that, if you allow them, you don't get lots of informative links from you to authority sites (which would be good); you get lots of rubbish spam links from you to a bunch of scammy affiliate nonsense, crap pseudo-search pages and people selling weight loss rubbish. None of which have anything to do with the subject, so they don't help with PR, really. Of course, since they're outgoing links, they don't have as much effect as incoming links, so don't worry too much.

i am not sure but it seems help a bit but not for spamm, there is adifferent between spamming and comment right. So comment is good spamming is bad.