Abstract: To make people understand more clearly the essence of phase transition, the phase transition in electrorheological fluid is further discussed from two different sides. The previous discussion merely considered the at traction action resulting from the polarixation of the suspended particles but omit ted the actual repelling action. After having considered the repelling action, the obtained critical field, has relation to the repelling action among particles as well as to temperature and dielectric constant. The results obtaind can explain main characteristics of the experimental results.

Key words: electrorheological fluid, critical field, phase transition