Prime Minister David Cameron said he wanted to close a loophole that allows sexual predators to produce and possess "manuals" giving tips on how to identify victims, groom them, and evade capture.
"It's completely unacceptable that there is a loophole in the law which allows paedophiles to write and distribute these disgusting documents," Cameron said.
"I want to ensure we do everything we can to protect children - and that's why I am making them illegal," Cameron told Sunday Times.
In future, paedophiles will face the same kind of sanctions as extremists who download guides to bomb-making.
The move came as it emerged that a paedophile teacher drugged and abused up to 60 boys as young as 10 at a private school in London.
US national William Vahey, 64, who taught history and geography at Southbank International School between 2009 and 2013, committed suicide last month as FBI agents closed in.
The new law is expected to be in force by the time of the general election next year, and could be implemented in an amendment to the Obscene Publications Act 1959, according to the newspaper.
The Terrorism Act 2000 outlawed terrorist training manuals.
It is unclear how many documents meant to assist paedophiles exist online or how often they are downloaded.
But the National Crime Agency has found examples during its investigations, which have included advice on grooming victims and evading capture.
The government measure is set to feature in the Queen's Speech, the BBC reported.
Details of how the law might be changed are yet to be announced, but it is thought ministers will amend the Obscene Publications Act 1959 to close the legal loophole, it said.
But the government may put in place measures similar to those that outlaw training manuals which could be used by terrorists, and have led to prison sentences of up two years in some cases.