The boys - aged nine, 10 and 11 - were allegedly assaulted at their school in the Queanbeyan area of southern NSW between January 2024 and December 2025.
Two women, aged 63 and 65, and a 38-year-old man have been charged with one count of assault.
Another man, 46, was charged with three counts of assault.
Detectives began investigating in November 2025, with help from officers at the Department of Community Justice and Department of Education.
While the exact nature of the assaults is not known, the education department said the allegations were deeply concerning.
"Behaviour of this kind is unacceptable in any school," a spokesperson said.
"The school remains appropriately staffed, ensuring support and continuity of learning for students."
None of the four staff members are currently working at the school, which cannot be named for legal reasons.
The staff will also be investigated by the Professional and Ethical Standards Directorate.
The four teachers are expected to appear in Queanbeyan Local Court on April 21.
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