Teachers consider strike action as an entire generation of young teachers could be without an occupational pension
Schools face a potential exodus if staff are asked to pay higher contributions or work longer before retiring, the National Union of Teachers (NUT) said.
Experienced teachers in mid-career were most concerned, according to a union survey of 7,500 staff which found that nearly 72% of those aged 30 to 50 were likely to quit.
The survey comes as teaching unions warn that every school in England and Wales could be affected by planned strikes next term over pensions.
The NUT's survey found that more than 60% of teachers said pensions were "very important" in keeping them in the profession. Nearly 86% of staff under 25 said they were more likely to opt out of the scheme if told to pay more or work longer.
The NUT says this creates "the prospect of almost an entire generation of young teachers without occupational pension provision".
Delegates at the NUT annual conference in Harrogate, North Yorkshire, this weekend will ballot for a series of one-day strikes . The first could take place in June with more in the autumn term.
The vote comes after the schools minister, Nick Gibb, was heckled by members of a smaller union, the Association of Teachers and Lecturers (ATL), as he attempted to justify the pension reforms.
Christine Blower, general secretary of the NUT, said teachers were in the "first wave" of opposition to the austerity programme across the public sector.
"We are obviously particularly concerned about teachers' pensions, but across the TUC there is a major concern about pensions. We are looking to take action on that next term. But we envisage public sector workers in other schemes, the health service, local government, civil service scheme, will be engaging in action beyond the summer."
Blower said that nearly every school in England and Wales could be affected. The NUT, which has around 300,000 members who contribute to the pension scheme, last went on strike in 2008 over pay. That walkout was their first in 21 years and affected 2.5 million children.
ATL delegates voted to ballot for strike action over pensions. Both unions fear the changes will mean teachers working longer, paying increased contributions and receiving less when they retire.
The government says the cost of teacher pensions is forecast to rise from about £5bn in 2005 to almost £10bn by 2015. Ministers say reform is needed because of a combination of more teachers retiring and increased life expectancy.
The pension reforms, in a report by the former Labour minister Lord Hutton, include raising the normal retirement age for state employees from 60 to 66 by 2020. Final-salary schemes would be replaced by payments based on career averages.
The pension challenge comes as new figures from Labour appear to show that school funding will fall in real terms over the next three years.
Figures from the Commons library also appear to show that funding per pupil will fall by 1.1% in real terms by 2015. The figures cannot be verified independently as there was no explanation of the method used to calculate them.
The government says that the schools budget will rise in real terms for every year of the spending review period, while the overall budget for the department will fall by 3%.
In a speech to the NASUWT teachers' union, the shadow education secretary, Andy Burnham, is expected to say: "This Tory-led government's education policy consists of broken promises, incompetence and wrong-headed reforms.
"They said they had found more resources for schools – but the schools budget is going to fall every year for the next three years."
A Conservative spokesman said: "These figures are misleading. We are increasing the schools budget by £3.6bn. We are providing extra money to cope with a rising school population, while delivering on our pledge to provide an additional £2.5bn of funding for the pupil premium. The public sector pay freeze will also ensure more resources are focused on pupils.
"Andy Burnham has repeated his £1bn spending commitment. He must tell us where this money would come from or admit he would have to increase the record budget deficit his government left behind even further. So long as he and his colleagues continue to make unfunded spending commitments and oppose every single cut, the public will see Labour's naked opportunism for what it is."