Abstract: The rheological behavior of microalumina concentrated suspensions was studied.The result showed that the microalumina powder concertrated suspensions are the dilatant fluid of nonaggregating micropowder suspension.With the increase of the concentration of miccroalumina powder,the critical shear rate c of the suspension shifts to the value of lower shear rate.Owing to pseudo aggregation,the rheopexy phenomenon appears.The double thixotropic rings of the microalumina concentrated suspensions indicate that thixotropy and viscoelasticity coexist in this system.Through a small amplitude oscillatory experiment,it was verified that the viscoelasticity of the system increased with the incerase of the concentration of the microalumina concentrated suspensions.The relations of the storage and loss modulus vs.the radial frequency were explained with the kinetic theory of molecules.