Michael Gove has been accused of "shamefully neglecting" the nation's children and pushing ahead with reforms that will "damage" education.
Pupils are suffering as a result of the Education Secretary's policies, which have left teachers' morale at "rock bottom" with many choosing to leave the profession, according to Dr Mary Bousted, general secretary of the Association of Teachers and Lecturers (ATL).
In a stinging attack, she accuses Mr Gove of bringing the Government into disrepute by introducing reforms which ignore expert opinion and have no democratic mandate.
In her speech to ATL's annual conference in Liverpool, Dr Bousted will say that it is her "duty to castigate the man who is undermining everything we stand for."
Dr Bousted says that successive education secretaries have presided over "turbulence" in the education system, and teachers are used to dealing with the changes.
But she added: "Now, in 2013, every aspect of the curriculum you teach, the qualifications you prepare children to take, are under attack and review. Michael Gove should take heed. When the changes come so thick and fast, without time for consultation or even consideration; when the changes are so wrong-headed, so damaging to children's education, then the morale of the profession plummets."
Dr Bousted's speech also accuses the Government of forcing schools to become academies against their wishes, and claims that it is "paving the way for the wholesale transfer of our schools to the private sector if the Conservatives are in office after the next election."
"The Government rushed to legislate to allow schools to choose to become academies," she says. "But where is the democracy in forcing it on parents and the local community when the policy has never been approved by Parliament?"
A Department for Education spokeswoman said: "These accusations couldn't be further from the truth. For too long standards in our schools have been declining. We need to make sure we have an education system that is robust and rigorous, with exams and qualifications that match the world's best. This is surely something the ATL should be applauding.
"Mary Bousted claims that the academies programme has no democratic backing - this is nonsense. It was passed by Parliament and has been hugely popular, with more than a third of all secondary schools choosing to convert to enjoy the freedoms and autonomy it brings."