My husband plan to deploy less than a year .During the time i plan to go back to my country for More than 6 Month .Should i need to apply re entry permit? i m green Card holder.

I would contact the office to find out for sure. The rules are constantly changing.

I would not stay in my country for 6 months. Considering the situation with immigration right now. Fact is if its not necessary I would not travel for a while. But to answer your question if you must leave the US come back within 4 months to be on the safe side.