Hello dear, you have to pass higher secondary school examination(class 12 or equivalent)  conducted by respective boards with minimum of 75 percent or be in top 20 percentile. Then you are eligible for jee mains .

Hope this information helps you .

Good luck 

HELLO!MANIVANNAN

These are following elligiblity criteria for JEE MAINS 2019:

Candidates must have  passed class 12th exam or qualifying exam  in 2017 or 2018.

Candidates appearing in class 12th or in equivalent exam can appear in JEE MAINS 2019.

To know more about elligiblity criteria for jee mains 2019 visit given below site:

https://engineering.careers360.com/articles/jee-main-eligibility-criteria.