National Institute of Technology, Trichy is one of the best colleges among NITs. So undoubtedly the cutoffs will be quite high. There are certain criteria to get into a college- your category, if you are applying through Home state quota or All India quota. If you belong to general category, then cutoffs would be high. Now you haven't mentioned your category, so considering you as general candidate, you have to secure a rank within 5000 i.e. almost 99.6 percentile score if this is your home state quota and a rank within 1300 which means 99.9 percentile if you are applying through All India quota. Now this is according to last year's data and this year the cutoff might change. Try to score the more you can so that the admission can be hassle free. You can check the last year's cutoff here
http://engineering.careers360.com/articles/jee-main-cutoff-for-nit-trichy