The accident is understood to have happened on Monday evening (6 October), when the member of staff was working on a Manroland Lithoman web press.
Production was suspended at the factory as police and ambulance crews attended the scene.
The site is now back in production, but the press that was involved in the accident has been cordoned off as the Health and Safety Executive (HSE) conducts an investigation.
St Ives chief executive Brian Edwards said: "Our thoughts are with the engineer's family and friends at what must be an extremely difficult time for them."
A spokeswoman for the HSE confirmed that it was working closely with the police and was investigating the accident, but she said that no further details were available at this time.
Engineer killed in accident at St Ives' Peterborough plant
A maintenance engineer has died in an accident at St Ives Web's Peterborough magazine printing plant.