Sergeant Mark Andrews was caught on CCTV dragging Pamela Somerville, 59, across the floor of Melksham police station before shoving her into the cell.
Ms Somerville was arrested in July 2008 after being found asleep in her car. She was detained for failing to provide a sample for a breath test.
The CCTV footage shows her lying on the floor for a minute before struggling to get up with blood pouring from a head wound.
Former soldier Andrews was convicted of assault causing actual bodily harm after a trial at Oxford Magistrates' Court in July.
The 37-year-old, who was suspended on full pay after his conviction, was sentenced at the same court.
Ms Somerville was taken to Royal United Hospital in Bath and needed stitches in a gash above her eye.
Passing sentence, Deputy District Judge Peter Greenfield said Andrews had abused his position of trust and only a custodial sentence was appropriate.
He said: "In my view, you presided over an atmosphere of bullying and intimidation upon Ms Somerville which culminated in the cell later that morning."
The judge continued: "I regard that a gross breach of trust placed upon you by Ms Somerville. I consider that right thinking members of the public will be appalled and totally saddened by your actions as a police officer."
Balding Andrews, wearing a dark suit, was led from the court in handcuffs by two dock officers. Jeremy Barton, defending Andrews, immediately submitted papers for an appeal.
The court heard that Andrews, who is married with children aged four and two, joined Wiltshire Police around eight years ago and was promoted to sergeant in 2005.
Prior to joining the police, he had spent around nine years in the Army, reaching the rank of sergeant.