AB2O4 is one of the most investigated systems due to the interaction between electron, spin, orbital, and lattice, which lead to the anormal physical properties:a) the orbital ordering transition that originates from the localized B-site on a geometrically frustrated structure;b) the approach to the itinerant electron limit with decreasing B-B separation. Although various models have been proposed to explain the behavior, there is not yet a full consensus on the precise nature of the orbital ordering. FeFe2-xCrxO4 present an interesting property: the lattice constants are varied in the solid solutions of FeFe2O4 and FeCr2O4. In our previous study, the ground state should be decided by the competition of the itinerant electrons and the superexhange between A/B ions. In order to elucidate the complicated interactions, it is important to study the details of the dynamic response.