  We study the effects of interorbital hopping on orbital fluctuations and
Mott-Hubbard metal-insulator transition (MIT) in the two-orbital Hubbard model
within the extended linearized dynamical mean-field theory. By mapping the
model onto an effective model with different bandwidths through the canonical
transformation, we find that at half-filling, the increases of the interorbital
Coulomb interaction $U^{\prime}$ and the Hund's coupling $J$ drive the MIT, and
the critical $J_{c}$ for MIT increases with the lift of the inter-orbital
hopping integral $t_{ab}$. Meanwhile at quarter filling and in the strong
correlation regime, the system without $t_{ab}$ exhibits MIT with the
decreasing of $J$, and favors the orbital liquid ground state. However, the
system transits from metal to insulator with the increasing of t$_{ab}$,
accompanied with the rising of the orbital order parameter. These results show
the important role of the interorbital hopping in the orbital fluctuation and
orbital ordering.
