The accident happened at around 7am at Niederried bei Interlaken in the canton of Bern.
The victim was driving a vehicle attached to a trailer containing sheep when for unknown reasons it left the main road and hurtled 30 metres down the embankment, ending up on the railway tracks, Bern cantonal police said in a statement.
It was then hit by a train coming from Interlaken.
Emergency services arrived quickly, but the man was pronounced dead at the scene.
A medical problem could have been the cause of the accident, police said.
Two of the sheep in the vehicle trailer were seriously injured and had to be put down.
Rail services were disrupted on the line for five hours.
In a separate incident, a 27-year-old woman died on Monday when she lost control of her car and crashed into an electricity pylon in Künten in the canton of Aargau, 20 Minutes reported.
Cantonal police have opened an investigation into the reasons for the crash.