A woman has been caught driving more than six times over the legal blood alcohol limit after police spotted her five-year-old child hanging out of the back window of her car as she travelled along a West Australian road.

Manjimup police, in the state's south, were alerted by several members of the public after they complained about the woman's erratic driving on Friday afternoon.

Officers then spotted the 32-year-old driving on Rutherford Road, with an unrestrained boy in the back seat.

After police pulled the vehicle over, the boy ran from the car, with the woman then refusing to supply the child's details.

It will be alleged a breath test then showed the woman was more than six times over the legal limit.

Her licence was cancelled, a surrender notice served on her Holden Commodore, and the woman was charged with driving under the influence and failing to ensure a passenger aged between four to seven years was restrained.

She will appear before the Manjimup Magistrates Court on January 31.