  Motivated by the recent neutron diffraction experiment on $YVO_3$, we
consider a microscopic model where each $V^{3+}$ ion is occupied by two 3d
electrons of parallel spins with two fold degenerate orbital configurations.
The mean field classical solutions of the spin-orbital superexchange model
predicts an antiferro-orbital ordering at a higher temperature followed by a
C-type antiferromagnetic spin ordering at a lower temperature. Our results are
qualitatively consistent with the observed orbital phase transition at $\sim
200K$ and the spin phase transition at $\sim 114K$ in $YVO_3$.
