The footage, filmed by an onlooker, Katie McCrary screaming as she is struck at least 12 times within 30 seconds by the policeman, The Independent reported on Friday.
The officer also threatening to shoot her if she will not put her hands behind her back.
Police was called after reports of a woman begging for money from customers at a petrol station in Decatur in Georgia, Press TV reported.
The footage does not show what led to the use of brutal police force against the defenseless person, but it shows the officer repeatedly hitting the woman with the baton as he pins her down.
He is seen landing some of the blows as she struggles on the floor and others as she lies still.
The officer then is seen placing the baton on the back of the woman’s neck and pinning her down with his knee in her back.
He can be heard shouting "let go or I'll shoot you" as she grabs the baton while bystanders are seen shouting, "no, please don't shoot her.”
The video ends after the officer handcuffs the woman while she is repeatedly asking, "What did I do?"
US police have been under harsh criticism over fatal shootings of and brutality against several African Americans in recent years.
Fatal police shootings and other forms of violence against people of color have sparked massive protests across the US in recent years.