It happened at 11.50am today, when a Land Rover collided with a crash barrier and came off the A3 on the southbound side near Clanfield.
A police spokeswoman said: ‘No injuries have been reported, however two horses did sadly pass away at the scene.’
The road has now been reopened after being closed for the Land Rover and horsebox to be recovered.
Traffic information service Romanse has said that the closure caused delays of about 20 minutes.