Hi

Yes ,you are eligible for jee main with your qualification of 3 year diploma in engineering provided you fulfill rest of the criteria

This is because,

3 year diploma in Engineering which is approved  by either AICTE or a State Board of Technical Education is equivalent  to 10 + 2 in order to be eligible for both JEE main and JEE advanced examination

You can check the same in the list of equivalent examinations on the page number 11th of Information Bulletin released by NTA ,the link to download it is provided below:-

https://jeemain.nta.nic.in/webinfo2021/File/GetFile?FileId=1&LangId=P

For reference,

JEE main eligibility criteria is provided below :-

Eligibility criteria says that:-

--------) Qualification required :- to be eligible  for JEE mains  for BE or Btech you need 10+2/equivalent qualification with Physics,  mathematics and anyone of Chemistry or Biology or Biotechnology or Technical Vocational Subject.

-------) Passing year :- one is eligible for JEE main examination for consecutive three years starting from the year of appearing for 12th /equivalent examination

------) There is no age limit to be eligible

------) there is no minimum percentage requirement to be eligible for JEE Mains, you just need to have passed your 12th/equivalent

But yes,

To be eligible for  NITs, IIITs, CFTIs one needs at least 75% marks in class 12th /equivalent if belongs to General or OBC category or or at least 65% marks in class 12th if belongs to Sc or St category. For this year i. e 2021 this minimum percentage requirement of 75% - 65 % has been lifted off.

For detailed information about jee main eligibility criteria  go through our page, the link for which is provided below

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

Thankyou