The prestigious Sydney girls' school Ascham has replaced its headmistress Helen Wright citing "significant differences" between her and the school's senior staff, the Sydney Morning Herald has reported.

''It became apparent that there were significant differences in approach and style between the headmistress and her senior team and staff on how they engaged as a team, managed change, implemented our vision and educated our girls,'' said a letter from the chairman school's board, Diane Grady, to parents.

''Differences in our respective expectations for the role of the headmistress in managing a school of this size and complexity on a daily basis also emerged, combined with differences around the interpretation and application of school policies,'' it said.

Dr Wright was in the role for only one year after being recruited from Britain after a global search. She has been replaced by the school's deputy Andrew Powell.