The invention relates to an electrorheological fluid material, and particularly relates to an electrorheological fluid material of chromium ion-doped bismuth ferrite nanoparticles. Compared with the traditional materials, the obtained electrorheological fluid disperse-phase material is chromium ion-doped bismuth ferrite particles. The particles have multiferroic properties such as ferroelectric property, piezoelectricity and magnetic property, also have electric field response ability, and are beneficial to improvement of the mechanical value of the electrorheological fluid material under electric field excitation. Thus, the electrorheological fluid prepared from the material and methylsilicone oil has a strong electrorheological effect. The material is simple in preparation technology, available in raw materials, and easy to control component and performance. The shear stress of the electrorheological fluid prepared from 5%mol of chromium-doped bismuth ferrite under different electric field intensities is displayed in the drawing described in the specification.