The man who revolutionised the vacuum cleaner believes Mr Blunkett's decision to allow more 14-year-olds to drop design and technology contradicts Labour's "Cool Britannia" policy of encouraging creative industries.
And he also blames a combination of snobbery among educationalists and parental prejudice for the situation.
Since 1998, underachieving pupils have been allowed to drop design and technology, science or modern languages to free time for work-related learning.
The Government plans to extend this scheme in August to permit some average- or high-achievers to drop languages andor design to concentrate on other subjects.
Mr Dyson, in a letter in this week's TES, said: "I think we can call this a betrayal.
"I know that both Tony Blair and Gordon Brown are extremely keen on design and engineering. They know how vital it is and how much our industry has ignored design and technology to its peril. I would be very surprised if they supported this change."
Mr Dyson, who is quoted in the Government's new curriculum document as a high-profile supporter of Design and Technology, said that during his school days he had not taken metal or wood work because because they were seen as being for the "thickos".
"When the term 'the three Rs' was coined in 1841 it meant 'Reading, Wroughting and Arithmetic'. Academics since then have been trying to substitute 'writing' for 'wroughting', because they don't like the sound of it. This move is just part of the same process."
A spokesman for the Department for Education and Employment said the greater flexibility at 14 would allow enthusiastic design and technology students to drop modern languages to concentrate on the subject.