Hubert Pragnell, who has taught history of art at King's School in Canterbury for the last 28 years, said the new syllabus has been dumbed down and does not have the same academic rigour of previous years.
He said: "It's like throwing Shakespeare out of the English A-level syllabus because it is considered old-fashioned.
"My experience is that these artists have inspired the young and are not out of date at all."
Mr Pragnell said the popularity of the Vermeer exhibition at the National Gallery showed many people still value traditional artists. He said he regretted that areas of the history of art syllabus had been left out now that the Assessment and Qualifications Alliance board's syllabus is the only one on offer.
Topics covered by the new syllabus, to be introduced this September, include looking at the planning and construction of museums and 20th century women artists.
"I feel that the 17th and 18th century is being pushed aside by more modern and trendy topics. Great as they may be, 20th century women artists is a limited subject. The great artists of the preceding 300 years should not be ignored," said Mr Pragnell.
George Turnbull of the Assessment and Qualifications Alliance said Mr Pragnell was wrong to suggest that older artists are being missed out of the new syllabus.
"There is plenty of choice to study whatever artist you want," he said. One section of the syllabus means that students can study an artist of their choice from painting, architecture or sculpture.