A wheelchair user was asked to prove he could walk a few paces by Legoland staff before being allowed on his favourite ride.
Five-year-old Sebby Brett, from Gloucestershire, suffers from an undiagnosed medical condition which has left him unable to walk without help.
He was asked to walk three paces before being allowed on the Ninjago ride in case of an evacuation, his mother said.
Legoland apologised for any distress but said the policy was “necessary”.
Joanna Brett said Lego-mad Sebby was made to get up from his wheelchair and walk holding just her hand.
Once he had completed the steps he was told by staff that he had to do it again, because they were not satisfied with his first attempt, Mrs Brett said.
“It was humiliating, and a totally arbitrary number,” said Mrs Brett.
After they finished on the ride, her son asked her: “Why would they make a disabled person walk? It really hurt.”
Mrs Brett said despite booking a disabled pass, staff at the park had not made her aware there would be any accessibility issues.
The family has called on the Windsor theme park to review its policies and to train its staff better on how to deal with disabled children.
A spokesman for the park said on some rides such as Ninjago “guests are required to walk unaided in case of guests being evacuated from the ride”.