Which book should i study from - ncert or maharashta state board books for BITSAT (i am a mah state board student )

Maharashtra State board is typically considered to be a notch lower than the CBSE syllabus
BITSAT exam preparation would be closer to CBSE syllabus than Maharashtra State Board syllabus so it is advised that you go with NCERT books
But this alone will not be enough
I'd suggest that you also go through the following books
1. A Complete Success Package for Online BITSAT (With CD) : Comprehensive Coverage of NCERT Syllabus for Classes 11 and 12 (English) 4th Edition -
Arihant Publication
2. BITSAT Explorer (With CD) (English) - MTG Editorial Board
3. BITSAT English Proficiency & Logical Reasoning PB (English) - Disha Experts

Good luck!