Former embattled Department of Parliamentary Services boss Carol Mills has broken down in front of a parliamentary committee and called for future secretaries of the department not to be subjected to personal attacks and continual reviews.

Senators decided to stop questioning 40 minutes into her voluntary appearance to give evidence about the performance of the department after she became tearful while answering a question about whether she thought her termination last month was unfair.

Ms Mills received a $380,000 early-loss-of-office payment when her job was terminated but did not tell the committee the reasons she was given for losing her job.

Loss of office payments cannot be made if a person has been sacked because of misbehaviour or unsatisfactory performance, according to the Remuneration Tribunal.

She detailed a job that put people under so much constant, unproductive scrutiny that well-respected people in the Australian public service thought the role of DPS secretary was impossible to do.

"If DPS is to move forward, this must include considering why it is three well-credentialled DPS secretaries ... have been criticised for their endeavours in campaigns that have become increasingly personal," she said.

During her own long public service career she had managed thousands of staff and budgets of more than $1 billion.

"It's also important to consider why so many informed people in the APS and elsewhere warned me against accepting this position because, in their view, under current arrangements, the job could not be done," she said.

Ms Mills hoped no successors would be placed in same situation.

She said constant reviews into DPS and rapid management turnover hurt the department's plans for the future.

"I've been buoyed by the personal amount of support I've received since last August when the clerk of the senate released a damaging intervention into an overseas recruitment process I was involved in," Ms Mills said in reference to her job application to become UK House of Commons clerk.

At the time, Dr Rosemary Laing wrote a letter to Commons Clerk Sir Robert Rogers.saying the appointment of Ms Mills would be "bizarre", "embarrassing" and an "affront".

In the committee hearing on Wednesday, Ms Mills said she had received good wishes from a "plethora of current and former senior politicians and public servants, academics and business people".

"They've all asked similar questions, what is wrong with the job at Parliament House? Didn't the same thing happen to people before you? Why are these attacks so personal?" she said.

Her predecessor, Alan Thompson, retired early in January 2012 amid a senate committee probe into allegations of DPS maladministration and bullying in the department. Another DPS secretary, Hilary Penfold, left in 2007 after reportedly clashing with senior Labor figures.

She hoped no successors were placed in the same situation.

In December, a Senate privileges committee found Ms Mills misled the Senate when giving evidence about the use of CCTV footage to spy on staff who visited a senator - a finding Ms Mills disputes.

Other dramas that plagued DPS during her time as secretary included controversy over the awarding of a photographic contract to Sydney's Anne Zahalka - who lives in the same street as Ms Mills - because there was little transparency about how it was awarded.

Senator John Faulkner has called DPS the "worst run government department in the Commonwealth of Australia".