Is jee mains is must for selection in btech?

Yes, you will need a valid JEE Main score to apply for B.Tech at GJU. The institute shortlists students based on their JEE scores and the final selection is done through counseling. The counseling is conducted by the Haryana State Technical Education Society (HSTES). 

You need to have passed 10+2 with at least 45% in order to be eligible for admission.