Atoya Montague filed the claim Thursday in British Columbia Supreme Court, the Canadian Broadcasting Corp. reported.
The lawsuit alleges that Inspector Tim Shields exposed himself to Montague several times and made unwanted sexual advances.
"While driving and in control of the vehicle, the defendant Shields, showed the plaintiff his erection through his jean shorts and made sexual advances towards the plaintiff, asking the plaintiff to have sex with him and advising her that he could easily pull over the car so that he could perform oral sex on her," the lawsuit said of one incident.
Montague, who went on sick leave and was diagnosed with post-traumatic stress disorder in 2012, said she did not report any of the incidents because she feared negative repercussions. The RCMP's health services has since harassed her about her condition and threatened to cut off her medical leave and pay, Montague said.
On Thursday evening the RCMP issued a statement saying it knew of the lawsuit and had opened an internal investigation into the matter.
"While the RCMP has not been officially served, it is our understanding the civil suit contains a series of serious but currently unproven, uncorroborated, and unsubstantiated allegations," said the statement released by Inspector Ed Boettcher.