Kelly Hespe says the department did not adequately supervise Sergeant Gerald Breimon after he was accused of sexually abusing a woman in 2003.
Those charges were later dropped.
Hespe says Breimon harassed her over a four-year period when he was her direct supervisor.
He and the police department are named in the lawsuit along with a police lieutenant.
"Even in my own home I haven't felt safe, I worry about my kids all the time. I have nightmares all the time about it," Hespe said.
The Chicago Police Department has not had the opportunity to review the claims, but said once they do, they will "proceed in the best interest of taxpayers."