  We consider the competition between the Kondo screening effect and
ferromagnetic long-range order (FLRO) within a mean-field theory of the Kondo
lattice model for low conduction electron densities $n_{c}$. Depending on the
parameter values, several types of FLRO ground states are found. When
$n_{c}<0.16$, a polarized FLRO phase is dominant. For $0.16<n_{c}<0.82$, a
non-polarized FLRO phase appears in the weak Kondo coupling region; while in
the intermediate coupling region the ground state corresponds to the polarized
and non-polarized FLRO phases, respectively, coexisting with the Kondo
screening. For a strong Kondo coupling, the product of pure Kondo singlets is
the ground state. Moreover, we also find that a weak magnetic field makes the
pure Kondo singlet phase vanish, while the non-polarized FLRO state with the
Kondo screening spans a large area in the phase diagram.
