I want to know about required eligibility to apply for The National Aeronautics and Space Administration as an Astronaut

To become an Astronaut in The National Aeronautics and Space Administration you have to firstly passed 12th grade with physics , chemistry and mathematics subjects.

After 12th you have to take pass a Bachelor’s degree in biological science, engineering, mathematics or physical science from a recognized university.

Astronaut Candidate (Non-Piloting background)
You must pass Bachelor’s degree from an accredited institution in engineering, biological science, physical science, or mathematics. Quality of academic preparation is important.

You must have a Degree followed by at least 3 years of related,professional experience or at least 1,000 pilot-in-command time in jet aircraft.

Ability to pass the NASA long-duration space flight physical, which includes the following specific requirements:
Distant and near visual acuity: Must be correctable to 20/20, each eye
Blood pressure not to exceed 140/90 measured in a sitting position
Standing height between 62 and 75 inches

Citizenship Requirements
You must be citizens of the United States, applicants with valid U.S. dual-citizenship are also eligible.

You can also apply for jobs in NASA after passing graduation through an entrance exam which is held by the NASA for the recruitment of Scientists, Astronauts etc.