Do the hindus burn their children dead bodies

My research says, yes, children can be cremated. What age are you asking about?

Namaste,

In hindu antyeshi (last rights) cremation is very commonly practiced due to religious purposes in purifying the body.

Children and advanced sunnyasis are usually buried because they have no attachment to the material world.

To add... as far as age is concerned, this is usually up until age 5, when spiritual life is said to begin.