Whenever you leave a comment on other blogs having disqus commenting system, you will get a backlink. Also keep in mind that number of backlinks always matters rather than getting backlinks from page rank post or blogs.
I am asking suppose if the htmls are not allowed then leaving a simple comment will that get a link from disqus profile.
No, I dont think so it will be called as a genuine backlink, it will be same as a backlink using comes from any profiles from social networking sites. I have used disqus most of the times for commenting, however I have never seen a backlink showing for my site from it. You can try starting a discussion on disqus and inserting your links in that, maybe that can get some backlinks.
Getting backlinks from disqus is not so useful in terms of SEO. because all the backlinks coming from disqus are no follow backlinks. However it can help you to get some visits for your blog.
Thing is that the motivation for comments to get links reduces the value of the comment as they are so often not that relevant. We have all seen the traditional "I love your blog and what you say [link]." For this reason they are no follow as they are worthless. From a traffic point of view the time spent doing them maybe not worth it either unless you use the time honored system of actually contributing something worthwhile.
If you need link juice - it's useless, it's like links from social media, there's too much of them. And keep in mind that links left via Disqus form are coming from discus, it will have nothing to do with the page where you left a message. But Disqus is a good place to get real visitors. Relevant comments bring interested users, in this respect links from Disqus can be very efficient.
If i successfully submit a link in disqus , so google consider dofollow link or nofollow for my site?
I just checked Disqus. The links you place on comments are no-follow, so they won't be very useful; but the link on your profile page is followed, so it is not absolutely useless. So my advice would be: set up your Disqus account and place a link on your profile. Then go place some comments so your profile can get crawled and the link indexed. Once you reach that point you can either just leave things there or continue using Disqus as you wish.