The trio are accused of a total of 53 sex abuse offences at Swaylands School in Penshurst, Kent, between 1967 and 1993.
Kent Police said Colwyn Baker, 70, of Morningside, Edinburgh, faces 29 counts of indecent assault and five charges of buggery.
David Hennessy, 73, of King's Lynn, Norfolk, has been charged with 16 counts of indecent assault.
A third man, 61-year-old Nigel Putman, of Slough, Berkshire, is accused of three counts of indecent assault.
All three men will appear at Maidstone Magistrates' Court on March 11.