Philip Pullman has accused the Government of having an exams "fetish" that is "ruining" children's lives.
An education that focuses only on facts is a "terrible recipe for the destruction of the soul", the celebrated author warned.
In an interview with the Press Association, Pullman said he was concerned that youngsters' childhoods are being destroyed by a need to pass tests.
The His Dark Materials author said he believed that "the government or whoever is in charge of education has got it badly wrong".
"They seem to think the function of a book for example, a storybook or a poem, the function of that is to provide exercises for grammar and it's not, of course.
"The function of a book or a poem or a story is to delight, to enchant, to beguile."
Tests such as Sats should be ditched in favour of teachers and children reading for pleasure, he argued.
He went on: "They seem to be doing their best to ruin children's lives. We hear of the desperate straits that some children get into now, older children who are facing GCSEs and A-levels and so on. It's entirely unnecessary.
"Yes, we have to test children, at some stages of education. Of course we do. They have to have exams, but to make them a complete fetish and to make the very existence of the school depend on their success in the league tables is just monstrous. It's absolutely monstrous.
"There's no need for it whatsoever. It's damaging, it's destructive, it's entirely counter-productive."
Pullman added: "It's the government. It's those in charge of education. There are individual teachers in individual schools who are doing wonderful things, who understand the true purpose of education, which is to help us find instruction and delight and interest in everything that exists.
"But to drill the interest out of everything in education by making children pass tests, it's as if you want to destroy their childhood."
Referring to Thomas Gradgrind from Charles Dickens' Hard Times, who espouses the need to teach children "facts", Pullman said this approach is "a terrible recipe for the destruction of the soul".
Pullman, who is backing a Woodland Trust competition which asked youngsters to draw their own woodland "daemon", also said he believes there is still an "appetite for stories" in the modern world.
"Books are very good vehicles for stories because, well, of all the advantages of a book: it doesn't need a battery, it doesn't run out, it doesn't break if you drop it, you can see how far through you've got, you can flick through quickly and look at the pictures.
"All the advantages of a book as a piece of technology are unsurpassed."
The winners of the Woodland Trust competition have been rewarded with a description penned by Pullman of their hand-drawn daemon - a concept from his books which are a visible part of people's soul that take animal form.
He said the quality of the entries was very high, adding: "It was a very enjoyable thing. I've never actually done anything quite like that before, because all my work normally comes out of my own imagination."
A Department for Education spokesperson responded: "We want to unlock the world of reading for pupils so that every child can not only read and write to a high standard, but can also develop a love for reading that will last until adulthood.
"That is why improving literacy is at the heart of this government's drive to improve standards in our schools and assessments do play an important role in making sure children are taught well.
"And the results speak for themselves - young readers in England are now ranked among the best in the world and there are now 154,000 more six-year-olds on track to become fluent readers than in 2012."