The man was sitting in the back seat with three other adults and two children when he stuck his head out of the car window to vomit in Zhengzhou in Henan Province.
Neither the driver nor other people in the car noticed the horror until a 6-year-old sitting next to the victim suddenly found his head "disappeared", Shanghai Daily reported.
Medical workers were immediately called to the scene and they were shocked as well by the sight.
Witnesses said the headless man was still sitting on the seat with blood all over the place.
The head of the drunken man was found three kms away.
Initial investigation showed the man's head was caught in the gap between the car and a truck driving on the adjoining lane.