The memorial to the 11 men who lost their lives in the 2015 disaster was completed last summer on the banks of the River Adur, near the old Toll Bridge.
Alongside personalised arches representing each of the victims, a pair of benches with tables rested next to the river for visitors to use for quiet reflection.
Pictures taken this morning show the benches have been torn up from the ground and tossed down the bank of the Adur.
Some of the planks have also been snapped or torn apart.
The Shoreham Airshow tragedy saw 11 men lose their lives when a Hawker Hunter jet crashed onto the A27 during a display on the afternoon of Saturday, August 22, 2015.
The victims were Maurice Abrahams, 76, of Brighton, Dylan Archer, 42, of Brighton, Anthony Brightwell, 53, of Hove, Matthew Grimstone, 23, of Brighton, Matthew Jones, 24, of Littlehampton, James Graham Mallinson, 72, of Newick, Daniele Polito, 23, of Goring, Mark Reeves, 53, of Seaford, Jacob Schilt, 23, of Brighton, Richard Smith, 26, of Hove, and Mark Trussler, 54, of Worthing.
Sussex Police have been contacted for more information on the vandalism.