sir is ECE is a good trade
After b.tech I want to apply for government form like railway IES
plz give me suggestions
is ECE useful for private companies

Look, Clearly ECE is the branch to give you a maximum scope/opportunities, as you can opt for On-Campus or Off-Campus Placements of even Great Tech-Giants companies, and Core electronics jobs too!, So, less benefit in compare to CSE/IT branches, but definitely more than Mechanical, Civil and Electrical Engineering. Now After Gate Exams, ECE is not much preferred in PSUs but obviously it has more opportunities than CSE/IT, but less opportunities than Mechanical, Civil, and Electrical Engineering. In Govt. Jobs through IES too! It has more opportunities than CSE/IT but less than Civil, Mechanical and Electrical Engineering...On The Whole, ECE is that's why popularly called Evergreen Branch for a reason!
So, Don't Worry! You will get maximum opportunities but in a very vast and different fields...(not in particular like only Govt. Or only Product-based Companies placements...)
Go for it...Don't Let any doubt or second thought bother you!
Hope This Helps, Always Welcome, A very Good Luck! from a very Big Heart! :-)