Abstract: This paper presents a certain kind of adaptive control system structure witha variable reference model.Double loop control is used,with an available stablescheme as the adaptive loop.Various states of the reference model are fed back tothe input side of the whole System,and then the parameters of the referencemodel are changed,or the reference model may be made to fulfil a certain indexof optimum performance.Changes of the reference model are equivalent to changesof the reference input of the system.Therefore the stability of the adaptive sys-tem remains unchanged.This paper also presents simulation results and shows thatthis structure possesses a certain flexibility in improving the dynamic characteris-tics of the error response.