A 16-year-old boy with a nut allergy who died after eating a walnut biscuit at a Sydney school was tragically let down by the NSW education department systems meant to protect him, an inquest has heard.

Raymond Cho went into anaphylactic shock after he ate the biscuit baked by other students in a cooking class at Ashfield Boys' High School on May 19, 2011.

Nut allergy ... Raymond Cho died after eating a walnut biscuit at school.

He was taken to hospital, but died after he was taken off life support on May 24.

At the Glebe Coroner's Court on Monday, State Coroner Mary Jerram was told the education department and staff were aware that Raymond suffered from anaphylaxis and asthma.