Hello Mainak Nandi. Thanks for contacting Careers360 and we hope we will be able to answer your query. 

To the best of my knowledge, students who have passed from NIOS board can appear in any engineering entrance examination like JEE, BITSAT, etc.

No university or academic institution in India can refuse admissions to students on this basis. 

So, yes, you can very well prepare for IIT JEE. Hope this helps you and all the best!