This impact of tests to be lessened, Sir Jim Rose told the Children, Schools and Families select committee.
He spoke out although his remit excludes the assessment system, which he said deserved a separate inquiry.
Sir Jim said one thing he hoped to achieve was to instil in children a love of learning for its own sake.
Last week Children's Secretary Ed Balls said the national tests for 14-year-olds in England would be scrapped, following this summer's marking "shambles".
When he asked Sir Jim a year ago to review the curriculum, Mr Balls told him: "Your review is focused on the curriculum and is not considering changes to the current assessment and testing regime".
But Sir Jim - whose interim report is to be published in a couple of weeks - made a point of telling the committee:
"I absolutely agree that too much time is spent rehearsing tests.
"We must try and shake that off somehow or another."
