how much does the life cost , such as food, wtaer, elctresity, Rent a house for family (father, mather, one chiled ) . in the year in Changsha?

For renting a apartment in the city downtown area, the fare is around 1500 to 2000RMB an month.
For food price, if you can cook on your own, I think it may cost you about 800 to 1000RMB.
For other items, it is hard to tell in exact. Generally speaking, the water and the eletrocity cost about 100 to 200RMB per month.
As a whole for a month, you may need to spend about 3500 to 4000RMB.