Hello,Akash

The basic requirement to become an astronaut is :

All applicants should have earn a bachelors degree in engineering,biological science,physical science,mathematics,more  preference is given to masters or PhD qualification.

Applicants also need to meet the physical standards:blood pressure-140/90,height-62-75inches,distant visual acuity-at least 20/100 or better uncorrected that  is correctable to 20/20 each eye .

Applicants who wish to join or become an astronaut pilot should have flown atleast 1000 flight hours as the pilot-in-commond of a jet aircraft.

So after 10+2 you can join B.E from any field (Electronics,mechanical,computer,aeronautical,aerospace) after b.e go MS for more specialization.See to become a astronaut you need to keep your maths and physics strong with meeting all the other criteria specifies above.For B.E you start with giving entrance test like JEE MAINS,ADVANCE ,this would be your first.

hope your query is answered.

Hello
The agency's basic requirements are a bachelor's degree in engineering, biological science, physical science ,computer science or mathematics, followed by three years of professional experience (or 1,000 hours of pilot-in-command time in jet aircraft). Candidates also must pass NASA's astronaut physical examination.

Goodluck I hope this helps you

Dear student here I tell you eligibility criteria.
PilotAstronautMinimal Requirements. Pilotastronautsneed a minimum of a bachelor's degree in engineering, biological/physical sciences or mathematics. They also require a minimum of 1,000 hours pilot-in-command time in a jet aircraft.
Thank you..