Cameron's coalition government says the proposed changes are a vital part of its mission to cut a record deficit, but trade unions say the plans will force members will pay more and work longer for lower pensions.
Immigration staff, civil servants, health workers, lecturers and prison workers are expected to take part in the 24-hour strike, with possible disruption at Heathrow and other London airports.
There were also likely to be problems on the Eurotunnel linking England and France.
Unions said they expected 400,000 people to take part but government officials said they expected the number to be half that.
About 20,000 off-duty police officers -- who are banned from striking under British law -- are expected to rally in London against cuts to pay, conditions and staff numbers.
Francis Maude, the Minister for the Cabinet Office, said the government was doing everything it could to minimise disruption to the public and ensure key services remained open.
"It is very disappointing that a handful of unions insist on carrying on with futile strike action which will benefit no one," Maude said in a statement.
"We would urge these union leaders to reconsider their position. Pension talks will not be reopened and nothing further will be achieved through strike action."
The strike is the latest in a series since the Conservative-Liberal Democrat coalition came to power two years ago.
Up to two million public sector workers took part in the last major strike over pensions in November, unions said.
The coalition took a beating in mid-term local elections one week ago, adding to worries for Cameron after voters in France and Greece moved decisively against austerity at the weekend.
Setting out its policies for the coming year in the Queen's Speech on Wednesday -- read out by Elizabeth II in parliament on behalf of the government -- the coalition said it would focus on "economic growth, justice and constitutional reform."
But the speech added that the "the first priority will be to reduce the deficit and restore economic stability".