Hey Midhun Kumar, 

Yes Diploma student is elgible to write JEE mains, but you are only allowed to right when you have all cleared subjects in diploma. And you are not elgibe to NIT’s and IIIT’s. Diploma students are only elgible to write to get admission into IIT’s and if you qualify in JEE mains then you need to write JEE advnace to get admission in IIT.