ThispaperinvestigatestherelationshipbetweenstatefeedbackandHamiltonicanrealization.Firest,itisprovedthatacompletelycontrollablelinearsystemalwayshasastatefeedbackstateequationHamiltonianrealization.NecessaryandsufficientconditionsareobtainedforittohaveaHamiltonianrealizationwithnaturaloutput.ThensomeconditionsforanaffinenonlinearsystemtohaveaHamiltonianrealizationaregiven.someconditionsforanaffinenonlinearsystemtohaveaHamiltonianrealizationaregiven.Forgeneralizedoutputs,theconditionsofthefeedback,keepingHamiltonian,arediscussed.Finally,theadmissiblefeedbackcontrolsforgeneralizedHamiltoniansystemsareconsidered.