Three different kinds of closure model of fiber orientation tensors were applied to sumulate numerically the hydrodynamic stability of fiber suspensions in a channel flow.The effects of closure roodels and three-dimensional(3-D)orientation distribution of fibers on the results of stability analysis were examined.It is found that the relationship of the behaviro in hydrodynamic stability and the parameter of the fiber given by all the three models are the same.However,the attenuation of flow instability is most distinct using 3-D hybrid model because the orientation of the fiber departures from the flow direction,and least apparent using its 2-D counterpart for that the fibers show a tendency towards alignment with the flow direction in this case.