Hello Surya, 

If you are asking about B. Tech undergraduate admissions then there are only two ways to apply for NIT Trichy;

1. By Jee Mains: NIT allows admissions to candidates securing ranks in Jee Mains and the process is under JoSAA. This application process generally starts in 2nd week of June. 

2. By DASA(Direct Admission for Students Abroad) : In this scheme, one can get direct admissions through SAT score. 

Hope this will help. 

Feel free to ask, if any other query. 

Thanks