The invention discloses a sandal insole, a preparation method thereof and a sandal, and relates to the field of shoe materials. The sandal insole comprises a PU insole base material, and the PU insole base material is formed by reacting a material A and a material B; the material A comprises
bifunctional polytetrahydrofuran ether, micromolecular straight-chain
diol, branched-chain
diol, a chemical
foaming agent, a catalyst and polyether
silicone oil; the branched chain
diol is selected from at least one of 2-butyl-2-ethyl-1, 3-
propylene glycol and 2, 2, 4-trimethyl-1, 3-pentanediol, and the branched chain diol is selected from at least one of 2-butyl-2-ethyl-1, 3-
propylene glycol and 2, 2, 4-trimethyl-1, 3-pentanediol; the material B comprises an
isocyanate component A and an
isocyanate component B, the
isocyanate component A is obtained by reaction of
diphenylmethane diisocyanate,
polypropylene oxide glycol,
polypropylene oxide triol and
carbodiimide modified
diphenylmethane diisocyanate according to a specific ratio, and the isocyanate component B is
isophorone diisocyanate. The sandal insole has the advantages of excellent
seawater resistance, low
compression set rate, good mechanical properties and long service life.