  We investigate the steady-state phase transitions in an all-to-all
transverse-field Ising model subjected to an environment. The considered model
is composed of two ingredient Hamiltonians. The orientation of the external
field, which is perpendicular to the spin interaction, can be tuned to be along
either $x$ direction or $z$ direction in each ingredient Hamiltonian while the
dissipations always tend to flip the spins down to the $z$ direction. By means
of mean-field approximation, we find that the quasi continuous steady-state
phase transition is presented as a consequence of the merging of two branches
of steady-state solutions. The emergence of bistability is confirmed by
analyzing the steady-state behaviors of a set of finite-size systems which is
also revealed by the Liouvillian spectrum.
