I have downloaded an excel sheet from "Links to your site" option of Google Webmaster Tools.
Now how to identify which links are dead and which are nofollow.
There is any way to find dead links from the list becuase there are many links in the excel sheet and very hard to find few dead links from them.
It can be done only manually as I know
For no-follow links use tools like Smallseotools, and for dead link you can check broken links, or again use smallseotools for broken links, because as Google Caches our site the data in webmaster gets changes accordingly.
I can't say I've ever looked into this in detail, but as reputable search engines do not follow "nofollow" links, I would expect none of the links listed by Google to be "nofollow".
Dead links are links where the target page doesn't exist. The easiest way to find these on your site is to look at any 404 errors and check to see whether those pages no longer exist.
You can check out the following link for your problem:
Hello, if you want to find dead & nofollow links you can check out smallseotools & backlink checker.
If you want dead link through google webmaster then click the site traffic tab and check the external back link of your site which link have not any live information regarding your domain that link is a dead link.
I use ahrefs.com to check nofollow links because find such links in Google Webmaster Tool is difficult. You should visit "Crawl Errors" section in Google Webmaster Tool to know dead or 404 errors links.
ahrefs.com for free is limited some features, I think smallseotools is more powerful for Backlink Checker! If your blog is developed on WordPress, you can use Brokenlink checker plugin for checking/removing dead links.
Thanks to all who replied.
As the question has been answered, and the OP has never returned, I think it's time to close this thread.