Abstract: Aiming at researching and developing new compounded suspensions to sever as electrorheological fluid (ERF), a metal core/polymer coating compounded suspension for ERF has been designed according to the principle of media polarization. Based on this evolution,a series of metal core/high polymer coating compounded particles such as Zn/polystyrenebutylacrylate compounded particles, Ni/polystyrenebutyl acrylate compounded particles, Ni/polystyrene compounded particles, Zn/polystyrene compounded particles have been prepared adopting the emulsion polymerization together with the microencapsulation techniques as well as the acidalkali matching theory which was initially suggested by Fowkes(schematically depicted in Fig.1). The micromorphologies of these compounded particles were measured using scan electron microscophy(the SEM photography of Fig.2 exhibits the coated condition of these particles) and the ERF performance of these compounded particles have alse been carried out. The performance test results indicate that the mechanical properties (refer to Fig.5～10 ) and the stability of ERF were improved, i.e. shear strength was no less than 2 kPa and segregation resistance was intensified signi ficantly compared with that of metal core, which shows that these materials are promising for acting as ERF though further modification should be necessary. Besides, from the performance test results it is apparently found that different compounded suspensions made up of different metal cores or polymer coatings possess various mechanical properties,and explanations for this phenomenon will discussed in detail elsewhere.