The four board members stood down ahead of a review of services at Southern Health NHS Foundation Trust, which is due to be published next week.
The trust came under fire after Connor Sparrowhawk drowned at its Slade House facility in Oxford.
Its boss Katrina Percy resigned in October amid public pressure.
Previous interim chairman Tim Smart also stood down after he was criticised for creating a new job for Ms Percy.
Current interim chairman Alan Yates, said: "The trust leadership will need to look quite different if it is to meet the needs of patients and service users, as well as its stakeholders.
"Four non-executive directors have this week jointly offered their resignation from their posts so that the governors can, with my help, recruit to the need for all five new non-executive directors."
Mr Yates, previously the trust's improvement director, said the trust would also need to find a new chairman before he leaves in July.
The review looks at the trust's mental health, learning disability, and community physical health services.
"The board has identified the benefits of much greater inclusion of service users and carers in the organisation as well as the delivery of its services," Mr Yates said.
July 2013 - Connor Sparrowhawk, 18, drowns after an epileptic seizure at Oxford unit Slade House. An inquest later rules neglect contributed to his death
11 December 2015 - The BBC reveals details of a leaked Mazars report which highlights a "failure of leadership". Health Secretary Jeremy Hunt says he is "profoundly shocked"
17 December 2015 - The report is officially published and shows out of 722 unexpected deaths over four years, only 272 were properly investigated
6 April 2016 - The Care Quality Commission (CQC) issues a warning notice to significantly improve protection for mental health patients
29 April 2016 - A full CQC inspection report is published, which says the trust is continuing to put patients at risk
30 June 2016 - Following a review of the management team competencies, it is announced that Katrina Percy is to keep her job
29 July 2016 - The BBC reveals the trust paid millions of pounds in contracts to companies owned by previous associates of Ms Percy
30 August 2016 - Ms Percy announces she is standing down as chief executive, but is staying on in an advisory role
19 September 2016 - Interim chairman Tim Smart resigns after admitting he created a job for Ms Percy
7 October 2016 - Ms Percy resigns completely from the trust
All the non-executive directors of an NHS trust criticised for failing to properly investigate hundreds of deaths have resigned.