The invention relates to a polyanion
solid electrolyte, a preparation method thereof and a
solid-state battery, and belongs to the field of
energy storage batteries. The polyanion
solid electrolyte is AaM (3-a) / m (SO4) bE1-bGc; a is one of Li, Na and K; m is one or more of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Al, Ga, In, La and Y; e is one or more of SO4 < 2->, CO3 < 2->, NO3 <->, NO2 <->, PO4 < 3->, PO4 < 3->, CrO4 < 2->, MnO4 < 2->, SiO4 < 4->, SiO3 < 2->, BO3 < 3-> and TeO4 < 2->; g is a
halogen element; a is equal to 0-3, b is equal to 0-1, c is equal to 0-1, and m is the valence state of M cations. The
ion transmission capability of the polyanion solid
electrolyte is enhanced, and the
ionic conductivity is improved, so that the performance of a solid-state battery is improved.