The session was due to take place at Huntingdon Racecourse but flooding in many parts of Cambridgeshire led to it being called off.
A racecourse spokeswoman said staff decided it was "too dangerous for people to access it on flooded roads".
Health and safety trainer David Passfield said: "You have to laugh at the irony of it".
Delegates had been expecting to learn about complying with health and safety laws before the racecourse's own health and safety regulations kicked in and dampened their plans.
More on the flooding and other stories from Cambridgeshire
A risk assessment was carried out and the risk posed by the floodwaters was deemed too great, Mr Passfield said.
"There were concerns about people getting in and out and becoming stranded."
The health and safety trainer said his "face dropped" when he "realised the irony of the situation".
The event has been postponed until the end of the month.
A health and safety training event has been cancelled because of health and safety concerns.