The weak insulation characteristics of unsymmetric dimethyl hydrazine (UDMH) were improved by means of mixing with the insulating oil, which realized the electrorheological effect of UDMH suspension. The experimental study of UDMH suspension was conducted by an electrorheological test device, and the effects of different electric field intensity and alginic acid medium contents on the electrorheological characteristics of UDMH suspension were analyzed. The results show that, the mass flow rate of suspension decreases with increasing the medium mass fraction within and without electric field, but their variation trend is different.With the increase of the medium mass fraction, the mass flow rate without electric field decreases continuously, while the mass flow rate within electric field tends a fixed value, whose value is affected by the interaction of electric field intensity and medium mass fraction. When the content of alginic acid is 30% and the elctric field intensity is 2 kV·mm^-1, the electrorheological effect for the suspension with 5% UDMH is the best. The content of UDMH has a great influence on the suspension insulation, and the suspension in which UDMH content is less than 15%, can achieve the electrorheological effect.