  We show that the subregion entanglement Hamiltonians of typical excited
eigenstates of a quantum many-body system are approximately linear combinations
of local or quasilocal conserved quantities of the subregion. By diagonalizing
an entanglement Hamiltonian superdensity matrix (EHSM) for an ensemble of
eigenstates, we can obtain the subregion (quasi)local conserved quantities as
the EHSM eigen-operators with nonzero eigenvalues. For free fermions, we find
the number of nonzero EHSM eigenvalues is around the order of subregion volume.
In the interacting XYZ model (within sizes calculable), we find the nonzero
EHSM eigenvalues decay roughly in power law if the system is integrable, with
the exponent $s\approx 1$ if the eigenstates are extended, and $s\approx
1.5\sim 2$ if the eigenstates are many-body localized. For fully chaotic
systems, only two EHSM eigenvalues are significantly nonzero, the
eigen-operators of which correspond to the identity and the subregion
Hamiltonian.
