I want to send $ 400 000 to my son from my indian bank account ,who is on H1 visa at USA to buy a house. What are the procedure as per us laws and weather my son should inform to IRS he has received this amount from his father and any tax is applicable in USA .please reply.

I assume this is a gift? Here would be no tax involved, but your son might have to file form 3520 to report the gift.