| Let Sp2(Fq)be the set of isomorphism classes of superspecial abelian surfaces over a finite field Fq,where Fqis of even degree over the prime field Fpof characteristic p∈{2,3,5}.Use Galois cohomology,we reduce the problem of finding isomorphism classes of superspecial abelian varieties over a finite filed to the problem of finding isomorphism classes of lattices over some orders,then we calculate the isomorphism classes of such lattices,thus give the value of|Sp2(Fq)|when p∈{2,3,5}. |