can i get admision in second year in diploma course of polytechnics on the basis of 12th (frm bhse brd) through leet admision in polytecnic?

Yes of course. In fact students taking admissions into polytechnic after 12th are directly admitted to secong year. Be sure to complete your 12th with good marks, it's taken as an eligibility criteria in some polytechnics. MArk my answer as best if yout think you query is resolved. Good Luck!

i think not possible

I have doubts. bhse is not accepted by many govt recognized colleges / boards / universities for higher studies. Anyway you need to confirm this with Technical Board of your state e.g. www.dte.org.in in Maharashtra.