2, 20,000 top rankers from JEE Main will be eligible to take JEE Advanced .Students are selected on the basis of marks and category.

The JEE Main 2017 cutoff will be similar to the previous year ranging between 95 to 100. JEE Main Cutoff 2017 is  the minimum required scores that an applicant will have to secure in order to qualify JEE Main examination and to advance further into JEE Advanced 2017.

Previous Year's Official Cutoff Trends of JEE Main

General-100
OBC-70
SC-52
ST-48

To check in detail you can refer below link

JEE Main Cutoff