We study the problem of classification of polynomial Hamiltonians with a non-degenerate linearly stable singular point on the two-dimensional complex plane with respect to the action of the group of polynomial symplectic automorphisms. To each Hamiltonian one can associate the set of polynomials in three variables which are the components of the Birkhoff normal form of the Hamiltonian and a finite group which is the Galois group of a finite-dimensional extension of the fields generated by the polynomials. Using these objects we provide an equivalence criterion for two polynomial Hamiltonians.