I need such an unlimited internet connection which can fulfil my needs.I work in stock market live through odin software. So i need a fast and lowcost with unlimited download connection plan from bsnl broadband. Please advice me which plan is mostly appropriate for me.

do you work from Home or Office?

Get the home UL 750 plan.

It offers Unlimited 256 Kb/s Broadband.

If you work from office, the SAME thing costs 3000/ Month (thanks to the very thoughtful Indian government )

Odin can work on any connection which is stable and is reasonably fast ie. even a 64kbps connection can do. As Bhvm said, you UL 750 will work.