The woman who filed a sexual harassment claim against former deputy prime minister Barnaby Joyce says she is dismayed the National Party has made no findings against him.

Key points: Nationals make no finding against Barnaby Joyce over sexual harassment complaint

Nationals make no finding against Barnaby Joyce over sexual harassment complaint Complainant Catherine Marriott says she is extremely disappointed after the eight-month investigation

Complainant Catherine Marriott says she is extremely disappointed after the eight-month investigation Ms Marriott has welcomed an improvement in the Nationals' complaint handling process

West Australian Catherine Marriott went public with her sexual harassment allegation against Mr Joyce earlier this year, prompting an internal party investigation.

That investigation has been completed, but a determination about the complaint was unable to be made.

Ms Marriott released a statement saying she had been informed of the outcome and she was extremely disappointed.

"While dismayed at the finding, I am not surprised as the party never had the external processes in place to deal with a complaint of sexual harassment by a Member of Parliament," she said.

In a brief statement, the New South Wales Nationals confirmed the complaint had been finalised.

"The report will be kept confidential," the statement said.

'I was not prepared to walk past this kind of behaviour'

Mr Joyce resigned as deputy prime minister and Nationals leader in February.

He cited the revelation of the complaint against him as a reason for standing down, saying "it's quite evident that you can't go to the despatch box while issues like that are surrounding you".

Ms Marriott said the investigation found she was "forthright, believable, open" and "genuinely upset" by the incident.

"I'm extremely disappointed that after eight months of waiting, three trips to the east coast at my own expense to meet with the party, my name and confidential complaint being leaked to the national media and my personal life being upended, the National Party have reached a 'no conclusion' verdict," Ms Marriott said in a statement.

She said the only positive to come from "this harrowing experience" was that the Nationals had developed a much improved complaints handling policy.

She said she had strongly encouraged the party to develop the new approach.

"While it has come at enormous personal expense, I was not prepared to walk past this kind of behaviour any longer," she said.

"I am pleased I stood up for what I believed was right and I'm proud I found the courage to make a difference for other people who want to create influence through political circles in future."

WA Nationals Leader Mia Davies said she was disappointed there was no determination made despite a months-long investigation.

"The fact there has been no real finding after all this time will no doubt act as a deterrent for anyone else with genuine complaints to come forward in future" she said.

"I can only speak on behalf of the WA branch of The Nationals, but we take such matters extremely seriously.

"People need to feel confident that if they present a genuine complaint that it will be dealt with in a transparent and timely manner."

A spokesperson for Mr Joyce said he had "nothing to add" to his statement on the matter from earlier this year, which described the allegation against him as "spurious and defamatory".