Can I do my M.Tech in IIT even though I have not doney B.Tech in iit? For example if I completed my B.Tech aeronautical in private college?

Yes, you can pursue M.Tech at an IIT even if you have done your B.Tech in a private college, it can also be in aeronautical engineering. The only requirement to take admission in M. Techs in IITs is a GATE (Graduate Aptitude Test in Engineering) score.

Eligibility criteria for admission are not limit