Education Minister Dan Tehan has proposed a review of the Melbourne Declaration, which was nationally agreed to in 2008 and sets education goals for students.
AEU federal president Correna Haythorpe says a review is unnecessary as the goals have not been achieved.
"Yet Federal Education Minister Dan Tehan is determined to meddle with one of the blueprint documents guiding Australian education," she told AAP.
“Once again the Morrison Government is just shifting the goalposts instead of addressing the issues when it comes up short on reaching targets.”
The review is expected to be part of discussions when Australia's education ministers meet in Melbourne on Friday.
AEU has written to the ministers about the review and also provided a submission on it, saying the Melbourne Declaration is still valid.
The union is concerned by an attempt to reframe the declaration as a "national aspirational declaration” rather than a blueprint for action.
The original goals include promoting equity and excellence, and that all young Australians become successful learners, confident and creative individuals and active and informed citizens.
"The current focus of education council should be to ensure that the original and largely unfulfilled goals and priority areas for action detailed in the declaration are implemented," AEU's letter states.
Haythorpe says the education ministers should address the issues of fair funding for public schools and the "continued failure" of the national assessment system, NAPLAN.